rhomboid, a. and n.
(ˈrɒmbɔɪd)
Also 7 romboid.
[(1) ad. F. rhomboïde or late L. rhomboīdēs rhomboides; (2) ad. mod.L. rhomboideus.]
A. adj.
1. Having the form of a rhomb; spec. in Bot. (see quot. 1839).
| a 1693 Urquhart's Rabelais iii. xlix. 398 Some of these Plants are..Romboid. 1701 Grew Cosmol. Sacra i. iii. 14 Many other sorts of Stones are regularly figured;..the Selenites, of Parallel Plates, as in a Deck of Cards; and they are of a Rhombick Figure; Talk, of such as are Rhomboid. 1729 Woodward Fossils i. I. 70 A large Rhomboid Selenites. 1824 J. E. Smith Eng. Flora II. 11 Red Goosefoot. Leaves triangular, somewhat rhomboid. 1839 Lindley Introd. Bot. 457 Rhomboid, oval, a little angular in the middle. 1877 W. H. Dall Tribes of N.W. 59 Artistic implements of rhomboid or semi-lunar form. |
b. Comb., as rhomboid-oblong, rhomboid-ovate, rhomboid-ovoid adjs.
| 1824 J. E. Smith Eng. Flora II. 13 White Goosefoot. Leaves rhomboid-ovate. 1845 Lindley Sch. Bot. vii. (1858) 123 Fruit rhomboid-oblong. 1870 Hooker Stud. Flora 315 Leaves..rhomboid-ovoid. |
2. Cryst. = rhombic 2. Now rare.
| 1670 [see rhombic 2]. 1845 G. E. Day tr. Simon's Anim. Chem. I. 57 Prisms of the right rhomboid system. |
3. Anat. a. rhomboid muscle = rhomboideus. b. rhomboid ligament: the costo-clavicular ligament.
| 1834 J. Forbes Laennec's Dis. Chest (ed. 4) 21 So that the rhomboid and trapezius muscles are made quite tense. 1848 Quain Anatomy (ed. 5) I. 202 marg., Rhomboid ligament. Ibid. 296 To expose the rhomboid muscle and the levator scapulæ, the trapezius must be removed. |
B. n.
1. A quadrilateral figure having only its opposite sides and angles equal.
| 1570 Dee Math. Pref. a iiij b, Rhombe, Rhomboïd, Lunular, Ryng, Serpentine, and such other Geometricall figures. 1672 Boyle Virtues of Gems 91 Geometrically figur'd Bodies, shap'd like Rhombus's or Rhomboides. 1789 Mrs. Piozzi Journ. France I. 139 The hall of Justice..is two hundred and fifty-six feet long, and eighty-six broad; the form of it a rhomboid. 1809 W. Irving Knickerb. iii, Fine white sand, which was curiously stroked into angles, and curves, and rhomboids, with a broom. 1818 Kirby & Sp. Entomol. xv. (ed. 3) I. 501 When the bees enlarge the diameter of the cells.., the bottoms often consist of two rhomboids and two hexagons. 1846 M{supc}Culloch Acc. Brit. Empire (1854) I. 319 Its [sc. Ireland] figure approaches to that of a rhomboid. 1853 Herschel Pop. Lect. Sci. viii. §122 (1873) 344 If such a rhomboid be laid down on an inkspot on white paper. |
2. Cryst. A solid bounded by six equal and similar rhombic faces parallel two and two.
| 1800 tr. Lagrange's Chem. I. 300 Phosphate of Soda... Its most common form is that of a lengthened rhomboid, the faces of which are inclined towards each other. 1860 Tyndall Glac. i. i. 3 Calcspar may be cloven in three directions oblique to each other; that is, into rhomboids. 1878 Gurney Crystallogr. 28 A rhomboid has no symmetral line. |
3. Anat. = rhomboid muscle.
| 1835–6 Todd's Cycl. Anat. I. 370/2 In the horse the levator proprius scapulæ is the anterior part of the rhomboid. 1899 Allbutt's Syst. Med. VII. 210 The rhomboids..are often wasted. |