parabolicadj.n.

Brit.

/ˌparəˈbɒlɪk/, U.S.

/ˌpɛrəˈbɑlɪk/

Forms: late Middle English parabolik, 1600s–1700s parabolick, 1700s– parabolic.

Origin: A borrowing from Latin. Etymon: Latin parabolicus.

Etymology: < post-classical Latin parabolicus allegorical (4th cent.), relating to the parabola (in geometry; 1686 in a British source) < Hellenistic Greek παραβολικός figurative (Clemens of Alexandria) < ancient Greek παραβολή parable n. + -ικός -ic suffix. Compare Middle French, French parabolique (c1500 with reference to metaphorical speech, 1571 in geometry), German parabolisch (1608 or earlier with reference to metaphorical speech, 1715 or earlier in geometry).In sense A. 2b after German parabolisch (C. F. Klein 1871, in Math. Ann. 4 577). With parabolic conoid compare post-classical Latin conoides parabolicum:1656 J. Wallis Arithmetica Infinitorum Prop. iv Item, Pyramidoides vel Conoides Parabolicum..ad Prisma vel Cylindrum (super æquali base æquealtum) est ut 1 ad 2.

A. adj.

a. Of or relating to parabola (parabola n. 2) or simile; figurative, metaphorical. Now rare.

ΘΚΠ

society > leisure > the arts > literature > style of language or writing > figure of speech > figures of meaning > [adjective] > characterized by metaphor > metaphorical or figurative

figurative14..

figural?a1500

translated1511

figurate1548

tropological1555

metaphorical1563

tropical1565

tropic1569

translate1582

allusory1587

translative1589

allusive1593

metaphoric1597

transumptive1597

transferent1614

translatitious1637

analogic1638

tralatitious1645

parabolic1696

tropologic1796

transitive1810

transferred1863

c1449 R. Pecock Repressor (1860) 533 (MED) This Scripture..meeneth..of a mannys kunnyngis, purposis, and deedis, signified bi likenes in parabolik speche to the iȝe, the hond, and the foot.

1696 W. Whiston Disc. conc. Mosaick Hist. Creation 64 in New Theory of Earth Resolving the whole into a Popular Moral or Parabolick Sense.

1878 G. D. Boardman Creative Week 20 Creation..transcends all experience... Hence all the words describing Creation must, in the very nature of the case, be figurative or parabolic.

1935 W. H. Auden & J. Garrett Poet's Tongue I. p. ix Since psychological truth depends so largely on context, poetry, the parabolic approach, is the only adequate medium for psychology.

b. Of, relating to, or of the nature of a parable or parables; expressed by a parable; allegorical.

ΘΚΠ

society > leisure > the arts > literature > prose > narrative or story > parable, allegory, or apologue > [adjective]

allegoricc1395

allegorical1528

parabolical1563

apological1623

apologal1652

parabolary1652

Aesopic1664

parabolic1669

Aesopian1688

society > leisure > the arts > literature > style of language or writing > figure of speech > figures of meaning > [adjective] > allegorical

ghostlyOE

allegoricc1395

allegorical1528

parabolical1563

parabolary1652

parabolic1669

semi-parabolic1876

1669 T. Gale Court of Gentiles: Pt. I i. ii. 11 Traditions; which he wraps up in..parabolic..notions.

1804 J. Collins Scripscrapologia 96 And through each parabolic tract, Pursue the trail of moral fact.

1882 A. B. Bruce (title) The parabolic teaching of Christ, a systematic and critical study of the parables of Our Lord.

1949 Dict. National Biogr. 1931–40 402/2 The book has delicacy and integrity; but it is rhapsodical, elusive, and deliberately parabolic.

1978 J. P. Stern Nietzsche v. 103 The prophetic or parabolic nature of Christ's sayings does not impair their simple appropriateness to each individual person.

1994 H. Bloom Western Canon iii. xiii. 315 Lady Dedlock's flight into death is a pure romance narrative, a parabolic punishment of female transgressiveness by a male society.

a. Geometry. Of the form of or resembling a parabola; having a shape whose cross-section is a parabola; relating to the parabola.

ΘΚΠ

the world > relative properties > number > geometry > curve > [adjective] > of conic section > parabolical

parabolical?a1560

parabolic1649

parabolar1665

paraboliform1710

1649 C. Cavendish Let. 5 Oct. in J. Pell Corr. with C. Cavendish (2005) 540 To finde a right line æquall to a parabolick line.

1681 N. Grew Musæum Regalis Societatis (1694) i. ii. 20 The extream part of the Shell next the Tail [of an armadillo], is Parabolick.

1749 D. Hartley Observ. Man i. iii. 357 The parabolic Area equal to ⅔ of the circumscribing Parallelogram.

1822 J. Imison Elem. Sci. & Art I. 19 The resistance of the air and other causes occasion projected bodies to deviate considerably from the parabolic curve.

1872 R. A. Proctor Ess. Astron. iii. 40 Comets which sweep round the sun in parabolic or hyperbolic orbits.

1938 Z. Grey Raiders Spanish Peaks xi. 220 He threw Harriet in a parabolic curve far over his head.

1942 J. C. Slater Microwave Transmission vi. 273 The focusing property of the parabolic mirror.

1991 Metalworking Production Sept. 91/1 The process will also work those shapes difficult to form or deep draw, such as conical, parabolic or re-entrant shapes.

b. Astronomy. Of space: Euclidean. Now chiefly in parabolic space n. at Compounds. rare.With reference to the geometry of space, the usual terms are elliptic, Euclidean, and hyperbolic.

ΘΚΠ

the world > relative properties > number > geometry > [adjective] > branches of

stereometrical1656

Apollonian1704

Euclidean1714

isoperimetrical1743

stereotomical1828

stereotomic1860

stereometric1862

graphic1865

parabolic1872

metageometrical1882

pangeometrical1882

Riemannian1889

synthetic1889

polygonometric1890

Lobachevskian1896

topological1913

1872–3 W. K. Clifford Math. Papers (1882) 189 That geometry of three-dimensional space which assumes the Euclidian postulates has been called by Dr. Klein the parabolic geometry of space, to distinguish it from two other varieties which assume uniform positive and negative curvature respectively, and which he calls the elliptic and hyperbolic geometry of space.

B. n.

1. A curve, figure, or object of parabolic form; a parabola or paraboloid. rare.

ΘΚΠ

the world > relative properties > number > geometry > curve > [noun] > conic section > parabola

parabola1559

parabolic1657

parabole1676

1657 W. Rand tr. P. Gassendi Mirrour of Nobility v. 100 Whether those..are the portions of Globes or of Parabolicks [L. parabolanum], or other figures, is truely hard to judge.

1807 R. Southey Lett. from Eng. II. 137 They were talking of parabolics and elliptics.

1985 Ann. Assoc. Amer. Geographers 75 568/2 The most common dune form I observed in northeastern Colorado is parabolic. Compound and modified parabolics..are also found.

†2. A parabolic expression, a metaphor. Obsolete.Apparently an isolated use.

ΘΚΠ

society > leisure > the arts > literature > style of language or writing > figure of speech > figures of meaning > [noun] > allegory > an allegory

likenessc1175

parablec1250

proverbc1384

similitudea1425

allegoryc1450

semblable1547

allusion1548

mythology1603

parabolic1829

1829 Blackwood's Edinb. Mag. 26 736 The grandeur of the house was above all parabolics.

Compounds

parabolic asymptote n. Geometry a parabolic line that continually approaches a given curve but does not meet it at any finite distance.

ΚΠ

1788 Chambers's Cycl. (new ed.) Parabolic asymptote,..a parabolic line approaching to a curve, so that..by producing both indefinitely, their distance from each other becomes less than any given line.

1898 Philos. Trans. (Royal Soc.) A. 191 152 The dotted lines represent the rectilinear and parabolic asymptotes.

1927 Proc. Royal Soc. 115 193 There is one branch extending to infinity in this direction, with a parabolic asymptote.

parabolic branch n. Geometry a branch of a curve which, like a parabola, extends to infinity without approaching an asymptote; contrasted with hyperbolic branch at hyperbolic adj. 2a.

ΚΠ

1871 E. Olney Gen. Geom. & Calculus iv. 137 This is a parabolic branch and approaches to parallelism with [the line] AT.

1988 SIAM Jrnl. Appl. Math. 48 144 The vector K belongs to the ‘parabolic’ branch of the dispersion curve.

† parabolic conoid n. Geometry Obsolete a paraboloid of revolution.

ΘΚΠ

the world > relative properties > number > geometry > shape or figure > [noun] > three-dimensional > solid of revolution > formed from curve

conoida1664

paraboloid1677

parabolic conoid1702

spindle1706

hyperboloid1743

1702 J. Raphson Math. Dict. Paraboloid... This is otherwise called a Parabolick Conoid.

1807 C. Hutton Course Math. (ed. 5) II. 274 A diving bell, of the form of a parabolic conoid.

1872–3 Chambers's Encycl. 125/2 The spherical reflector occupies the place of the parabolic conoid which has been cut off behind the parameter.

parabolic microphone n. a microphone having a parabolic pattern of sensitivity.

ΘΚΠ

the world > physical sensation > hearing and noise > audibility > sound magnification or reproduction > [noun] > microphone

carbon transmitter1878

microphone1878

carbon microphone1879

pantelephone1881

phonoscope1890

mike1911

condenser microphone1921

magnetophone1922

radio microphone1922

ionophone1924

crystal microphone1925

ribbon microphone1925

radio mike1926

laryngophone1927

velocity microphone1931

ribbon mike1933

pressure microphone1934

bug1936

eight ball1937

ribbon1937

throat microphone1937

throat mike1937

rifle microphone1938

parabolic microphone1939

lip microphone1941

intercept1942

spike mike1950

spy-mike1955

spy-microphone1960

mic1961

rifle mike1961

gun microphone1962

spike microphone1962

shotgun microphone1968

Lavallière1972

wire1973

sneaky1974

multi-mikes1990

1939 Sci. Monthly Mar. 289/2 (caption) Sight and sound are picked up by the iconoscope camera and parabolic microphone and sent through separate cables to the control room.

1977 P. Hill Fanatics 38 Could we have a parabolic microphone in the control flat?

1998 New Yorker 1 June 41/1 Parabolic microphones..permit listening from a football field away.

parabolic point n. Geometry (originally) a point on a surface at which the indicatrix is a parabola, i.e. where a plane parallel to, and an infinitesimal distance from, the tangent plane at that point intersects the surface in a parabola; (now) a point on a surface at which the Gaussian curvature is zero.

ΚΠ

1866 W. T. Brande & G. W. Cox Dict. Sci., Lit. & Art II. 799/2 Parabolic point, a point on a surface at which the indicatrix is a parabola... The parabolic points..lie on a non-plane curve of the 4n(n−2)^th order. The tangent plane at a parabolic point is of the kind called stationary.

1948 Amer. Jrnl. Math. 70 333 (title) Differential geometry of a surface at a parabolic point.

1990 Proc. London Math. Soc. 60 412 (0, 0, 0) is not a parabolic point of M..however the boundary inflects the critical set.

† parabolic pyramidoid n. Geometry Obsolete a pyramid-like solid on a square base whose sections through opposite corners of the base are parabolas (rather than triangles as in a pyramid).

ΘΚΠ

the world > relative properties > number > geometry > shape or figure > [noun] > three-dimensional > cone > pyramid

pyramid1570

tetrahedron1570

pyramidate1611

parabolic pyramidoid1704

pyramidoid1704

pyramoid1819

1656 J. Wallis De Sectionibus Conicis Prop. ix. 23 in Operum Math. De Conoide, & Pyramidoide Parabolico.]

1704 J. Harris Lexicon Technicum I Parabolick Pyramidoid..so named by Dr. Wallis from its Genesis, or Formation.

parabolic reflector n. a reflector for light, sound, radio waves, etc., made in the form of a paraboloid of circular cross-section so as to reflect parallel rays to a focus, or produce a parallel beam from a source at the focus.

ΚΠ

1826 Philos. Trans. (Royal Soc.) 116 328 A large plano-convex lens..being substituted for a parabolic reflector.

1899 G. Marconi in Jrnl. Inst. Electr. Engineers 28 274 Should it be necessary to direct a beam of rays in one given direction I prefer to use an arrangement similar to a Righi oscillator placed in the focal line of a suitable cylindrical parabolic reflector.

1962 A. Nisbett Technique Sound Studio i. 23 An assembly consisting of a cardioid or omnidirectional microphone fitted at the focus of a parabolic reflector is also strongly directional.

1986 G. Langley Telecommunications Primer (ed. 2) xxiii. 70 A parabolic reflector (often called a dish) can be used to provide a very directional high-gain antenna with the radio energy concentrated into a parallel beam.

parabolic space n. †(a) Geometry the space contained within the finite arc of a parabola cut off by a chord (obsolete); (b) Astronomy (now rare) = Euclidean space at Euclidean adj. (see sense A. 2b).

ΚΠ

1706 Phillips's New World of Words (new ed.) Parabolick Space, is the Area..between the Curve..of the Parabola and any entire Ordinate.

1872–3 W. K. Clifford Math. Papers (1882) 236 (note) According to Dr. Klein's nomenclature, a space, every point of which can be uniquely represented by a set of values of n variables, is called elliptic, parabolic, or hyperbolic, when its curvature is uniform and positive, zero, or negative.]

1878 Amer. Jrnl. Math. 1 354 The geometry of the points at an infinite distance in a flat or parabolic space.

1967 Philos. Trans. (Royal Soc.) A. 262 301 An example of a parabolic space is a fibre bundle M over a Riemannian space B, together with a connexion on M.

parabolic spindle n. Geometry a solid figure formed by the revolution of a finite arc of a parabola about its chord (a double ordinate).

ΚΠ

1706 Phillips's New World of Words (new ed.) Parabolick Spindle.

1869 Sci. Amer. 20 Nov. 325/3 An oblate spheroid, or a parabolic spindle, would encounter less atmospheric resistance, in passing through the air, than a ball or globe.

1923 Amer. Math. Monthly 30 192 The mensuration of solids deals with..parabolic spindle and the ‘cylindrical ring’.

parabolic spiral n. Geometry a two-armed spiral in which the length of the radius vector is proportional to the square root of the angle it makes with a fixed line (originally formed by deforming a parabola so that its axis became a circle while the ordinates remained perpendicular to the axis); formerly also called helicoid parabola.

ΚΠ

1704 J. Harris Lexicon Technicum I Helicoid Parabola, or the Parabolick Spiral, is a Curve which arises from the Supposition of the Axis of the common Apollonian Parabola's being bent round into the Periphery of a Circle.

1852 C. Davies Elem. Differential & Integral Calculus (new ed.) viii. 179 Hence, (u−r)²=2pt, is the equation of the parabolic spiral.

1928 Amer. Math. Monthly 35 378 Discuss the modes of the parabolic spiral (ρ−a)²=caθ.

This entry has been updated (OED Third Edition, June 2005; most recently modified version published online March 2022).

单词	parabolic
释义	parabolicadj.n. Brit. /ˌparəˈbɒlɪk/, U.S. /ˌpɛrəˈbɑlɪk/ Forms: late Middle English parabolik, 1600s–1700s parabolick, 1700s– parabolic. Origin: A borrowing from Latin. Etymon: Latin parabolicus. Etymology: < post-classical Latin parabolicus allegorical (4th cent.), relating to the parabola (in geometry; 1686 in a British source) < Hellenistic Greek παραβολικός figurative (Clemens of Alexandria) < ancient Greek παραβολή parable n. + -ικός -ic suffix. Compare Middle French, French parabolique (c1500 with reference to metaphorical speech, 1571 in geometry), German parabolisch (1608 or earlier with reference to metaphorical speech, 1715 or earlier in geometry).In sense A. 2b after German parabolisch (C. F. Klein 1871, in Math. Ann. 4 577). With parabolic conoid compare post-classical Latin conoides parabolicum:1656 J. Wallis Arithmetica Infinitorum Prop. iv Item, Pyramidoides vel Conoides Parabolicum..ad Prisma vel Cylindrum (super æquali base æquealtum) est ut 1 ad 2. A. adj. 1. a. Of or relating to parabola (parabola n. 2) or simile; figurative, metaphorical. Now rare. ΘΚΠ society > leisure > the arts > literature > style of language or writing > figure of speech > figures of meaning > [adjective] > characterized by metaphor > metaphorical or figurative figurative14.. figural?a1500 translated1511 figurate1548 tropological1555 metaphorical1563 tropical1565 tropic1569 translate1582 allusory1587 translative1589 allusive1593 metaphoric1597 transumptive1597 transferent1614 translatitious1637 analogic1638 tralatitious1645 parabolic1696 tropologic1796 transitive1810 transferred1863 c1449 R. Pecock Repressor (1860) 533 (MED) This Scripture..meeneth..of a mannys kunnyngis, purposis, and deedis, signified bi likenes in parabolik speche to the iȝe, the hond, and the foot. 1696 W. Whiston Disc. conc. Mosaick Hist. Creation 64 in New Theory of Earth Resolving the whole into a Popular Moral or Parabolick Sense. 1878 G. D. Boardman Creative Week 20 Creation..transcends all experience... Hence all the words describing Creation must, in the very nature of the case, be figurative or parabolic. 1935 W. H. Auden & J. Garrett Poet's Tongue I. p. ix Since psychological truth depends so largely on context, poetry, the parabolic approach, is the only adequate medium for psychology. b. Of, relating to, or of the nature of a parable or parables; expressed by a parable; allegorical. ΘΚΠ society > leisure > the arts > literature > prose > narrative or story > parable, allegory, or apologue > [adjective] allegoricc1395 allegorical1528 parabolical1563 apological1623 apologal1652 parabolary1652 Aesopic1664 parabolic1669 Aesopian1688 society > leisure > the arts > literature > style of language or writing > figure of speech > figures of meaning > [adjective] > allegorical ghostlyOE allegoricc1395 allegorical1528 parabolical1563 parabolary1652 parabolic1669 semi-parabolic1876 1669 T. Gale Court of Gentiles: Pt. I i. ii. 11 Traditions; which he wraps up in..parabolic..notions. 1804 J. Collins Scripscrapologia 96 And through each parabolic tract, Pursue the trail of moral fact. 1882 A. B. Bruce (title) The parabolic teaching of Christ, a systematic and critical study of the parables of Our Lord. 1949 Dict. National Biogr. 1931–40 402/2 The book has delicacy and integrity; but it is rhapsodical, elusive, and deliberately parabolic. 1978 J. P. Stern Nietzsche v. 103 The prophetic or parabolic nature of Christ's sayings does not impair their simple appropriateness to each individual person. 1994 H. Bloom Western Canon iii. xiii. 315 Lady Dedlock's flight into death is a pure romance narrative, a parabolic punishment of female transgressiveness by a male society. 2. a. Geometry. Of the form of or resembling a parabola; having a shape whose cross-section is a parabola; relating to the parabola. ΘΚΠ the world > relative properties > number > geometry > curve > [adjective] > of conic section > parabolical parabolical?a1560 parabolic1649 parabolar1665 paraboliform1710 1649 C. Cavendish Let. 5 Oct. in J. Pell Corr. with C. Cavendish (2005) 540 To finde a right line æquall to a parabolick line. 1681 N. Grew Musæum Regalis Societatis (1694) i. ii. 20 The extream part of the Shell next the Tail [of an armadillo], is Parabolick. 1749 D. Hartley Observ. Man i. iii. 357 The parabolic Area equal to ⅔ of the circumscribing Parallelogram. 1822 J. Imison Elem. Sci. & Art I. 19 The resistance of the air and other causes occasion projected bodies to deviate considerably from the parabolic curve. 1872 R. A. Proctor Ess. Astron. iii. 40 Comets which sweep round the sun in parabolic or hyperbolic orbits. 1938 Z. Grey Raiders Spanish Peaks xi. 220 He threw Harriet in a parabolic curve far over his head. 1942 J. C. Slater Microwave Transmission vi. 273 The focusing property of the parabolic mirror. 1991 Metalworking Production Sept. 91/1 The process will also work those shapes difficult to form or deep draw, such as conical, parabolic or re-entrant shapes. b. Astronomy. Of space: Euclidean. Now chiefly in parabolic space n. at Compounds. rare.With reference to the geometry of space, the usual terms are elliptic, Euclidean, and hyperbolic. ΘΚΠ the world > relative properties > number > geometry > [adjective] > branches of stereometrical1656 Apollonian1704 Euclidean1714 isoperimetrical1743 stereotomical1828 stereotomic1860 stereometric1862 graphic1865 parabolic1872 metageometrical1882 pangeometrical1882 Riemannian1889 synthetic1889 polygonometric1890 Lobachevskian1896 topological1913 1872–3 W. K. Clifford Math. Papers (1882) 189 That geometry of three-dimensional space which assumes the Euclidian postulates has been called by Dr. Klein the parabolic geometry of space, to distinguish it from two other varieties which assume uniform positive and negative curvature respectively, and which he calls the elliptic and hyperbolic geometry of space. B. n. 1. A curve, figure, or object of parabolic form; a parabola or paraboloid. rare. ΘΚΠ the world > relative properties > number > geometry > curve > [noun] > conic section > parabola parabola1559 parabolic1657 parabole1676 1657 W. Rand tr. P. Gassendi Mirrour of Nobility v. 100 Whether those..are the portions of Globes or of Parabolicks [L. parabolanum], or other figures, is truely hard to judge. 1807 R. Southey Lett. from Eng. II. 137 They were talking of parabolics and elliptics. 1985 Ann. Assoc. Amer. Geographers 75 568/2 The most common dune form I observed in northeastern Colorado is parabolic. Compound and modified parabolics..are also found. †2. A parabolic expression, a metaphor. Obsolete.Apparently an isolated use. ΘΚΠ society > leisure > the arts > literature > style of language or writing > figure of speech > figures of meaning > [noun] > allegory > an allegory likenessc1175 parablec1250 proverbc1384 similitudea1425 allegoryc1450 semblable1547 allusion1548 mythology1603 parabolic1829 1829 Blackwood's Edinb. Mag. 26 736 The grandeur of the house was above all parabolics. Compounds parabolic asymptote n. Geometry a parabolic line that continually approaches a given curve but does not meet it at any finite distance. ΚΠ 1788 Chambers's Cycl. (new ed.) Parabolic asymptote,..a parabolic line approaching to a curve, so that..by producing both indefinitely, their distance from each other becomes less than any given line. 1898 Philos. Trans. (Royal Soc.) A. 191 152 The dotted lines represent the rectilinear and parabolic asymptotes. 1927 Proc. Royal Soc. 115 193 There is one branch extending to infinity in this direction, with a parabolic asymptote. parabolic branch n. Geometry a branch of a curve which, like a parabola, extends to infinity without approaching an asymptote; contrasted with hyperbolic branch at hyperbolic adj. 2a. ΚΠ 1871 E. Olney Gen. Geom. & Calculus iv. 137 This is a parabolic branch and approaches to parallelism with [the line] AT. 1988 SIAM Jrnl. Appl. Math. 48 144 The vector K belongs to the ‘parabolic’ branch of the dispersion curve. † parabolic conoid n. Geometry Obsolete a paraboloid of revolution. ΘΚΠ the world > relative properties > number > geometry > shape or figure > [noun] > three-dimensional > solid of revolution > formed from curve conoida1664 paraboloid1677 parabolic conoid1702 spindle1706 hyperboloid1743 1702 J. Raphson Math. Dict. Paraboloid... This is otherwise called a Parabolick Conoid. 1807 C. Hutton Course Math. (ed. 5) II. 274 A diving bell, of the form of a parabolic conoid. 1872–3 Chambers's Encycl. 125/2 The spherical reflector occupies the place of the parabolic conoid which has been cut off behind the parameter. parabolic microphone n. a microphone having a parabolic pattern of sensitivity. ΘΚΠ the world > physical sensation > hearing and noise > audibility > sound magnification or reproduction > [noun] > microphone carbon transmitter1878 microphone1878 carbon microphone1879 pantelephone1881 phonoscope1890 mike1911 condenser microphone1921 magnetophone1922 radio microphone1922 ionophone1924 crystal microphone1925 ribbon microphone1925 radio mike1926 laryngophone1927 velocity microphone1931 ribbon mike1933 pressure microphone1934 bug1936 eight ball1937 ribbon1937 throat microphone1937 throat mike1937 rifle microphone1938 parabolic microphone1939 lip microphone1941 intercept1942 spike mike1950 spy-mike1955 spy-microphone1960 mic1961 rifle mike1961 gun microphone1962 spike microphone1962 shotgun microphone1968 Lavallière1972 wire1973 sneaky1974 multi-mikes1990 1939 Sci. Monthly Mar. 289/2 (caption) Sight and sound are picked up by the iconoscope camera and parabolic microphone and sent through separate cables to the control room. 1977 P. Hill Fanatics 38 Could we have a parabolic microphone in the control flat? 1998 New Yorker 1 June 41/1 Parabolic microphones..permit listening from a football field away. parabolic point n. Geometry (originally) a point on a surface at which the indicatrix is a parabola, i.e. where a plane parallel to, and an infinitesimal distance from, the tangent plane at that point intersects the surface in a parabola; (now) a point on a surface at which the Gaussian curvature is zero. ΚΠ 1866 W. T. Brande & G. W. Cox Dict. Sci., Lit. & Art II. 799/2 Parabolic point, a point on a surface at which the indicatrix is a parabola... The parabolic points..lie on a non-plane curve of the 4n(n−2)^th order. The tangent plane at a parabolic point is of the kind called stationary. 1948 Amer. Jrnl. Math. 70 333 (title) Differential geometry of a surface at a parabolic point. 1990 Proc. London Math. Soc. 60 412 (0, 0, 0) is not a parabolic point of M..however the boundary inflects the critical set. † parabolic pyramidoid n. Geometry Obsolete a pyramid-like solid on a square base whose sections through opposite corners of the base are parabolas (rather than triangles as in a pyramid). ΘΚΠ the world > relative properties > number > geometry > shape or figure > [noun] > three-dimensional > cone > pyramid pyramid1570 tetrahedron1570 pyramidate1611 parabolic pyramidoid1704 pyramidoid1704 pyramoid1819 1656 J. Wallis De Sectionibus Conicis Prop. ix. 23 in Operum Math. De Conoide, & Pyramidoide Parabolico.] 1704 J. Harris Lexicon Technicum I Parabolick Pyramidoid..so named by Dr. Wallis from its Genesis, or Formation. parabolic reflector n. a reflector for light, sound, radio waves, etc., made in the form of a paraboloid of circular cross-section so as to reflect parallel rays to a focus, or produce a parallel beam from a source at the focus. ΚΠ 1826 Philos. Trans. (Royal Soc.) 116 328 A large plano-convex lens..being substituted for a parabolic reflector. 1899 G. Marconi in Jrnl. Inst. Electr. Engineers 28 274 Should it be necessary to direct a beam of rays in one given direction I prefer to use an arrangement similar to a Righi oscillator placed in the focal line of a suitable cylindrical parabolic reflector. 1962 A. Nisbett Technique Sound Studio i. 23 An assembly consisting of a cardioid or omnidirectional microphone fitted at the focus of a parabolic reflector is also strongly directional. 1986 G. Langley Telecommunications Primer (ed. 2) xxiii. 70 A parabolic reflector (often called a dish) can be used to provide a very directional high-gain antenna with the radio energy concentrated into a parallel beam. parabolic space n. †(a) Geometry the space contained within the finite arc of a parabola cut off by a chord (obsolete); (b) Astronomy (now rare) = Euclidean space at Euclidean adj. (see sense A. 2b). ΚΠ 1706 Phillips's New World of Words (new ed.) Parabolick Space, is the Area..between the Curve..of the Parabola and any entire Ordinate. 1872–3 W. K. Clifford Math. Papers (1882) 236 (note) According to Dr. Klein's nomenclature, a space, every point of which can be uniquely represented by a set of values of n variables, is called elliptic, parabolic, or hyperbolic, when its curvature is uniform and positive, zero, or negative.] 1878 Amer. Jrnl. Math. 1 354 The geometry of the points at an infinite distance in a flat or parabolic space. 1967 Philos. Trans. (Royal Soc.) A. 262 301 An example of a parabolic space is a fibre bundle M over a Riemannian space B, together with a connexion on M. parabolic spindle n. Geometry a solid figure formed by the revolution of a finite arc of a parabola about its chord (a double ordinate). ΚΠ 1706 Phillips's New World of Words (new ed.) Parabolick Spindle. 1869 Sci. Amer. 20 Nov. 325/3 An oblate spheroid, or a parabolic spindle, would encounter less atmospheric resistance, in passing through the air, than a ball or globe. 1923 Amer. Math. Monthly 30 192 The mensuration of solids deals with..parabolic spindle and the ‘cylindrical ring’. parabolic spiral n. Geometry a two-armed spiral in which the length of the radius vector is proportional to the square root of the angle it makes with a fixed line (originally formed by deforming a parabola so that its axis became a circle while the ordinates remained perpendicular to the axis); formerly also called helicoid parabola. ΚΠ 1704 J. Harris Lexicon Technicum I Helicoid Parabola, or the Parabolick Spiral, is a Curve which arises from the Supposition of the Axis of the common Apollonian Parabola's being bent round into the Periphery of a Circle. 1852 C. Davies Elem. Differential & Integral Calculus (new ed.) viii. 179 Hence, (u−r)²=2pt, is the equation of the parabolic spiral. 1928 Amer. Math. Monthly 35 378 Discuss the modes of the parabolic spiral (ρ−a)²=caθ. This entry has been updated (OED Third Edition, June 2005; most recently modified version published online March 2022). < adj.n.c1449
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