rhomb
(rɒmb, rɒm)
Also 6 rombe, 7 rhombe, romb, roumb, 8 rumb.
[ad. L. rhombus rhombus. Cf. F. rhombe (1542 in Hatz.-Darm.).]
1. Geom. A plane figure having four equal sides and the opposite angles equal (two being acute and two obtuse). Also, a lozenge-shaped object or formation; Nat. Hist., etc., a part, disposition of parts, marking, etc., of this shape.
pectinated rhomb: a hydrospire.
| c 1578 in Hakluyt Voy. (1600) III. 43 We builded a little house..and garnished it with many kinds of trifles, as Pinnes, Points, Laces, Glasses, Rombes. 1597 Morley Introd. Mus. Annot. ¶4 The semibriefe was at the first framed like a triangle,..but..it grew afterward to the figure of a rombe or loseng. 1671 Milton P.R. iii. 309 See how in warlike muster they appear, In Rhombs and wedges, and half moons, and wings. 1696 Phillips, Rhomb, or Roumb. 1726 Swift Gulliver iii. ii, If they would..praise the Beauty of a Woman, or any other Animal, they describe it by Rhombs, Circles,..and other geometrical Terms. 1727–38 Chambers Cycl. s.v. Neper's bones, By adding the several numbers occurring in the same rhomb together. 1794 Kirwan Elem. Min. (ed. 2) I. 259 Garnet..presenting either 12 rhomboidal planes, or 24 trapezoidal, or 36 planes, of which 12 are rhombs. 1818 Kirby & Sp. Entomol. xv. (ed. 3) I. 489 For the solution of this problem the geometrician..found that the great angles of the rhombs should be 109° 26{p}, and of the small angles 70° 34{p}. 1849 H. Miller Footpr. Creat. iii. (1874) 32 The more amply imbricated tile-like rhombs of the Dipterians and Palaeonisci. 1854 Murchison Siluria ix. 217 A pair of pectinated rhombs. 1855 in Orr's Circ. Sci., Inorg. Nat. 300 The rhombic dodecahedron is a solid, bounded by twelve equal and similar four-sided figures, called rhombs. 1859 Darwin Orig. Spec. viii. (1860) 229, I have noticed half-completed rhombs at the base of a just-commenced cell. |
2. Cryst. A solid figure bounded by six equal and similar rhombic planes; a rhombohedron.
| 1800 tr. Lagrange's Chem. I. 305 [It] will crystallize..in the form of a rhomb. 1813 Bakewell Introd. Geol. (1815) 48 Calcareous stalactites..cleave into regular rhombs. 1831 Brewster Optics xvii. 144 A rhomb of Iceland spar. 1869 Tyndall Notes Lect. Light §419 When a small aperture through which light passes is regarded through a rhomb of Iceland spar two apertures are seen. |
b. Fresnel's rhomb: see
quot.| 1854 Pereira's Polarized Light (ed. 2) 105 Fresnel effected the circular polarization of light by means of a parallelopiped of St. Gobin (crown) glass.., whose acute angles B and C are about 54° and consequently whose obtuse ones A and D are about 126°. This apparatus is commonly called Fresnel's rhomb. |
† 3. A circle; a magic circle.
Obs. rare.
| 1656 Blount Glossogr. [after Cotgr.], Rhomb, a Spinning Wheel, Reel, or Whirle. 1667 Milton P.L. viii. 134 That swift Nocturnal and Diurnal rhomb suppos'd, Invisible else above all Starrs, the Wheele of Day and Night. 1697 Abell in Potter Antiq. Greece iv. x. 269 [tr. Ovid Amores i. viii. 7–8], She knows the Rhomb, what Feats in Magick are From th' pois'nous Issue of a lustfull Mare. |
† 4. ? A turbot.
Obs. rare.
| 1720 Strype Stow's Surv. II. xxvii. 366/2 [transl. statute for buying fish], A Piece of Rumb, gross and fat, for 4d. |
5. Conch. (See
quot. and
cf. rhomb-shell.)
| 1815 E. J. Burrow Conch. 200 Porphyria, Large clouded Rhomb or Camp Olive. Oliva, Yellow Rhomb; Olive. Paupercula, Zebra Rhomb. |
6. attrib. and
Comb., as
rhomb-marked,
rhomb-shaped adjs.;
rhomb-dodecahedron, a rhombic dodecahedron;
rhomb-ovate a., partly rhomboid and partly ovate;
rhomb-porphyry, a porphyry enclosing crystals of orthoclase of a rhombic outline (Cassell);
rhomb-shell Conch., a volute;
rhomb-solid, a solid figure consisting of two equal right cones joined together at their bases and generated by the revolution of a rhomb upon a diagonal;
rhomb-spar [G.
rhomboidalspath], see
quot. 1837.
| 1895 Maskelyne Crystallogr. 195 Diamond, gold, and electrum are among the substances that occur in *rhomb-dodecahedra. |
| 1877 Nature XV. 326/2 Three *Rhomb-marked Snakes (Psammophylax rhombeatus) from South Africa. |
| 1793 Martyn Lang. Bot. (ed. 2), Rhombeum folium, a Rhombed or *rhomb-shaped leaf. 1796 Withering Brit. Plants (ed. 3) II. 483 Petals rhomb-shaped. |
| c 1711 Petiver Gazophyl. 8/1 A White Indian *Rhomb-shell finely speckled with black. 1815 E. J. Burrow Conch. 200 Voluta, Rhomb Shell or Cylinder. |
| 1704 J. Harris Lex. Techn. I, *Rhombe Solid. |
| 1804 Jameson Syst. Min. I. 516 Calc Genus. Seventh Species. *Rhomb-spar. 1837 Dana Min. 197 The names Rhomb spar and Bitter spar, have been applied to the perfectly crystallized specimens [of dolomite], excepting those with curved faces and a pearly lustre, which have been designated Pearl spar. |