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parallelogram|pærəˈlɛləgræm|
[a. F. parallélogramme (1552 in Hatz.-Darm.), ad. L. parallēlogrammum, a. Gr. παραλληλόγραµµον n., neut. of παραλληλόγραµµος bounded by parallel lines, f. παράλληλος parallel + γραµµή line.]
1. Geom. A four-sided rectilineal figure whose opposite sides are parallel; sometimes spec. applied to a rectangle.
1570Billingsley Euclid i. xxxiv. 44 There are fower kindes of parallelogrammes, a square, a figure of one side longer then the other, a Rhombus, or diamond figure, and a Rhomboides or diamondlike figure. 1611Cotgr., Paralelogramme, a Paralelogramme, or long Square. 1646Sir T. Browne Pseud. Ep. 60 A parallelogram or long square figure. 1726Swift Gulliver iii. ii, Cones, cylinders, parallelograms, and several other mathematical figures. 1806Hutton Course Math. I. 288 Parallelograms..on the Same Base, and between the Same Parallels, are equal to each other. 1846Ellis Elgin Marb. I. 71 The plan of the generality of the temples of Greece, was that of a simple parallelogram.
b. parallelogram of forces (Dynamics): a figure illustrating the theorem that if two forces acting at one point be represented in magnitude and direction by two sides of a parallelogram, their resultant will be similarly represented by the diagonal drawn from that point; hence, a name for the theorem itself. So parallelogram of velocities, etc. [F. parallélogramme des forces, Lagrange Méc. Anal. (ed. 2, 1811).]
1830Kater & Lardner Mech. v. 50 To verify experimentally the theorem of the parallelogram of forces is not difficult.
2. A thing shaped like the figure described in 1.
†a. An old name for the pantograph n. Obs.
c1656in Sir W. Petty Down Survey (1851) Pref. 16 These reducements were made by paralelagrames. 1668Pepys Diary 27 Oct. 1704J. Harris Lex. Techn. I, Parallelogram,..an Instrument made of five Rulers of Brass or Wood, with Sockets to slide or set to any Proportion, used to enlarge or diminish any Map or Draught. 1723,1727–41[see pantograph n.].
b. Anything of this form, or whose section is of this form, as a block of buildings, a space of ground (cf. square), a brick, card, domino, etc.
1820Syd. Smith Wks. (1859) I. 303/1 Mr. Owen may give his whole heart and soul to the improvement of one of his parochial parallelograms; but who is to succeed to Mr. Owen's enthusiasm? 1862Wilson Preh. Man ii. (1865) 14 This [site] the original projectors of the city mapped off into parallelograms. 1873Tristram Moab ii. 21 Picture a parallelogram of canvas quite black, and with a roof only three or four feet above the ground.
3. attrib. and Comb.
1704J. Harris Lex. Techn. I, Parallelogram Protractor, is a Semicircle of Brass, with four Rulers, in form of a Parallelogram, made to move to any Angle; one of which Rulers is an Index, which shews on the Semi-circle the Quantity of any inward or outward Angle. 1767Monro in Phil. Trans. LVII. 497 Parallelogram-shaped crystals. 1842E. Miall in Nonconf. II. 809 Communities..shaped parallelogram-wise. |