helix
(ˈhɛlɪks, ˈhiːlɪks)
Pl. helices (ˈhɛlɪsiːz), helixes.
[a. L. helix, a. Gr. ἕλιξ anything of spiral form.]
1. Anything of a spiral or coiled form, whether in one plane (like a watch-spring), or advancing around an axis (like a corkscrew), but more usually applied to the latter; a coil, a spiral, as an electromagnetic coil of wire, the thread of a screw, a tendril, etc. In Geom., the curve formed by a straight line traced on a plane when the plane is wrapped round a cylinder; more generally, a curve on any developable surface (e.g. a cone) which becomes a straight line when the surface is unrolled into a plane; distinguished from spiral, which is applied only to plane curves.
| 1643 Sir T. Browne Relig. Med. i. §17 The lives..of men..and the whole world, run not upon a Helix that still enlargeth, but on a Circle. 1664 Power Exp. Philos. i. 8 [The butterfly's tongue] being drawn up into an Helix, and retracted into the mouth. 1792 T. Taylor Proclus I. 134 The helix..is described about a sphere or a cone. 1826 Henry Elem. Chem. I. 195 A copper wire, by being rolled round a solid rod, was twisted into a spiral so as to form a helix. 1837 Brewster Magnet. 156 An electro-magnetic helix enclosing a bar-magnet. 1854 J. Scoffern in Orr's Circ. Sc., Chem. 195 Take a flat helix of..wire. c 1860 Faraday Forces Nat. 189 Three wheels of magnets and two sets of helices. 1882 Vines Sachs' Bot. 866 The tendrils..form a spiral..or..a helix narrowing conically upwards. |
2. Arch., etc. A spiral ornament, a volute; spec. applied to the eight smaller volutes under the abacus of the Corinthian capital.
| 1563 Shute Archit. D iij d, Helices, the which..haue but halfe the height of the other great Helices, or Volutas. 1664 Evelyn tr. Freart's Archit. 128 At the extreams of the leaves do issue the Caules, and Codds breaking from the Helices. 1789 P. Smyth tr. Aldrich's Archit. (1818) 98 The greater one, under the horn of the abacus, is called the volute; the smaller one, under the flower, the helix. 1857 Birch Anc. Pottery (1858) II. 5 The development of the helix or ornament of the antefixae is very remarkable. |
3. Anat. The curved fold or prominence which forms the rim of the external ear.
| 1693 Blancard Phys. Dict. (ed. 2), Helix, the Exterior brim of the Ear, so called from its Winding. 1705 Phil. Trans. XXV. 1979 The Prominence called Helix ends in the Lobe of the Ear, which it constitutes. 1873 Darwin in Life & Lett. III. 324–5 The leaf on one side looks just like the helix of a human ear. |
4. Zool. A genus of molluscs with spiral shells, of which the common snail (Helix hortensis) is a typical example.
| 1820 Scoresby Acc. Arctic Reg. I. 180 Helices, and other genera of Mollusca. 1830 Lyell Princ. Geol. I. 384 Terrestrial shells, chiefly helices. 1866 Tate Brit. Mollusks iv. 94 The Helices do not live to a venerable age. |