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pyramidal, a. (n.)|pɪˈræmɪdəl|
[ad. med.L. pȳramidālis (Du Cange): see pyramid n. and -al1. Cf. F. pyramidal (1507 in Hatz.-Darm.).]
1. Of or pertaining to a pyramid; sloping, as an edge or face of a pyramid. rare.
1571Digges Pantom. iii. viii. R j b, The Pyramidall side HB. 1597R. Wrag Voy. Constantinople in Hakluyt Voy. (1599) II. i. 308 Two hils rising in a piramidall forme. 1762–71H. Walpole Vertue's Anecd. Paint. (1786) II. 90 Some were made of glass in a pyramidal shape. 1857J. G. Wilkinson Egypt. Pharaohs 151 The pyramidal, or sloping, line was intended to insure the durability of a wall.
2. a. Of the nature or shape of a pyramid; resembling a pyramid.
1599T. M[oufet] Silkwormes 45 A Pyramidall and most steepe hil. 1634Sir T. Herbert Trav. 61 High Pyramidall Cypresse-trees. 1678Cudworth Intell. Syst. i. i. 53 Plato..would compound the Earth of Cubical, and Fire of Pyramidal Atoms, and the like. 1784Cowper Task vi. 159 The Lilac various in array,..With purple spikes pyramidal. 1816Shelley Let. 22 July, Pr. Wks. 1888 I. 349 Conical and pyramidal crystallizations. 1874Motley Barneveld II. xxi. 385 One tall pyramidal gable of ancient grey brickwork.
fig.1641Milton Ch. Govt. vi. Wks. 1851 III. 128 Prelaty if she will seek to close up divisions in the Church, must be forc't to dissolve and unmake her own pyramidal figure. 1872W. Minto Eng. Prose Lit. ii. v. 368 That the most stable government is the pyramidal,—that rests on the widest basis of popular confidence.
b. fig. In journalistic use (after F. pyramidal): Astonishingly huge, colossal.
[1827C'tess Granville Lett. (1894) I. 432 Madame de Montjoie has just told me that Miss Foote's success is pyramidale.] 1902Westm. Gaz. 16 Aug. 3/2 The pyramidal ignorance of the average Englishman concerning the great Republic and her institutions.
3. Specific technical applications.
a. Anat. Applied to certain structures of more or less pyramid-like form, esp. to certain muscles in the abdomen, and in the nose (both often denoted by the L. pyramidalis used absol., sc. musculus). Also, Pertaining to or connected with the pyramids of the medulla oblongata, as in pyramidal tract, a tract of motor nerve-fibres in the spinal cord. Also Path. applied to a form of cataract in which the capsule of the crystalline lens is opaque and prominent at its centre.
[1693tr. Blancard's Phys. Dict. (ed. 2) s.v., Muscles of the Nostrils and of the Abdomen called Pyramidales, or of a Pyramidical Figure.] 1725Bradley's Fam. Dict. s.v. Nose, The Nostrils are dilated by six Muscles, three on each Side, viz. the pyramidal, oblique Ascendant or Myrtiformis, and the oblique descendant. 1872Darwin Emotions vii. 190 The pyramidal muscle serves to draw down the skin of the forehead between the eyebrows, together with their inner extremities. 1879Calderwood Mind & Br. ii. 26 The most important of the cells are known as pyramidal. 1899Allbutt's Syst. Med. VII. 732 Sclerosis of the pyramidal tracts.
b. Cryst. Used in senses 1 and 2; also applied to the tetragonal system, of which the square pyramid is a characteristic form.
1789J. K[eir] 1st Pt. Dict. Chem. 69/1 A brown salt, which..forms white, pyramidal crystals. 1828Stark Elem. Nat. Hist. II. 482 Fundamental forms of minerals... The Pyramidal, in which the crystals assume the form of an isosceles four-sided pyramid. 1851Richardson Geol. v. 97 The Pyramidal includes the octohedron with a square base, and the right square prism.
c. Applied to particular species of plants having the flowers in a pyramid-like spike or cluster (often translating the specific name pyramidalis); also to fishes or other animals having the body or some part of a pyramid-like form. pyramidal orchid or pyramidal orchis, an orchid, Anacamptis pyramidalis, which is native to Europe and North Africa, and bears dense spikes of deep pink flowers.
1778W. Hudson Flora Anglica (ed. 2) II. 383 Pyramidal Orchis. 1796C. Marshall Gardening xix. (1798) 355 Saxifrage plants are usually potted to move into the house..as indeed the pyramidal in particular should be. 1804Shaw Gen. Zool. V. 390 Pyramidal Sucker. Ibid. 425 Pyramidal Trunk⁓fish. 1858A. Irvine Illustr. Handbk. Brit. Plants 316 Pyramidal Orchis... Flowers in a very dense, short, ovate spike, of a beautiful rose colour. 1882Garden 11 Feb. 89/1 Other native Orchises, such as..the Pyramidal Orchis.., live and flower in a garden, but do not increase or improve. 1951V. S. Summerhayes Wild Orchids Brit. iii. 51 The pyramidal orchid is a very beautiful example of perfect adjustment to pollination by butterflies and moths. 1977M. Allan Darwin & his Flowers xi. 198 The Pyramidal Orchid..has its parts arranged very differently from Orchis mascula.
4. a. Arith. Applied to the several series of numbers, each beginning with unity, obtained by continued summation of the several series of polygonal numbers; so called because each of these numbers, represented (e.g.) by balls, can be arranged according to a certain rule in the form of the corresponding pyramid (on a triangular, square, or polygonal base).
Thus the series of triangular numbers, 1, 3, 6, 10, 15, 21..gives, by summation of successive terms, the series of triangular pyramidal numbers 1, 4, 10, 20, 35, 56... Similarly from the series of square, pentagonal, etc. numbers are obtained corresponding series of pyramidal numbers. The pyramidal numbers constitute the second (sometimes called the third) order of figurate numbers: see figurate ppl. a. 3 b. The term was formerly extended (with ordinal numeral) to the succeeding orders of figurate numbers, each obtained similarly from the preceding by continued summation: see 1795 in b. (In quot. 1674 erroneously used.)
1674S. Jeake Arith. (1696) 663 Six is called the first Pyramidal Number; for the Units therein may be so placed, as to represent a Pyramis. 1795Hutton Math. Dict., Pyramidal Numbers, are the sums of polygonal numbers, collected after the same manner as the polygonal numbers themselves are found from arithmetical progressions. 1806― Course Math. I. 224 Column c contains the sum of the triangular numbers, that is, the shot contained in a triangular pile, commonly called pyramidal numbers.
b. (as n.) A pyramidal number.
1706W. Jones Syn. Palmar. Matheseos 165 Pyramidals having their Names from their Number of Sides. 1795Hutton Math. Dict. s.v. Pyramidal Numbers, These are particularly called First Pyramidals. The sums of First Pyramidals are called Second Pyramidals;..and so on. Particularly, those arising from triangular numbers, are called Prime Triangular Pyramidals.
5. Comb., as pyramidal-shaped, adj.
1859W. S. Coleman Woodlands (1866) 108 The Yew forms a pyramidal-shaped tree. 1868Rep. U.S. Commissioner Agric. (1869) 202 A weeping, pyramidal-shaped plant.
Hence pyˈramidalist = pyramidist; spec. one who holds certain theories or beliefs about the pyramids of Egypt. So pyˈramidalism, the body of theories or beliefs held by pyramidalists.
1877Proctor Myths & Marvels Astron. 52 The facts most confidently urged by pyramidalists in support of their views. 1882― Gt. Pyramid i. 11 Taylor, Smyth, and the Pyramidalists generally, consider this sufficient to prove that the pyramid was erected for some purpose connected with religion. |