Crossword Dictionary

What's The Definition Of Spiral?

\Spi"ral\, a. [Cf. F. spiral. See {Spire} a winding line.] 1. Winding or circling round a center or pole and gradually receding from it; as, the spiral curve of a watch spring. 2. Winding round a cylinder or imaginary axis, and at the same time rising or advancing forward; winding like the thread of a screw; helical. 3. (Geom.) Of or pertaining to a spiral; like a spiral. {Spiral gear}, or {Spiral wheel} (Mach.), a gear resembling in general a spur gear, but having its teeth cut at an angle with its axis, or so that they form small portions of screws or spirals. {Spiral gearing}, a kind of gearing sometimes used in light machinery, in which spiral gears, instead of bevel gears, are used to transmit motion between shafts that are not parallel. {Spiral operculum}, an operculum whih has spiral lines of growth. {Spiral shell}, any shell in which the whorls form a spiral or helix. {Spiral spring}. See the Note under {Spring}, n., 4.
\Spi"ral\, n. [Cf. F. spirale. See {Spiral}, a.] 1. (Geom.) A plane curve, not re["e]ntrant, described by a point, called the generatrix, moving along a straight line according to a mathematical law, while the line is revolving about a fixed point called the pole. Cf. {Helix}. 2. Anything which has a spiral form, as a spiral shell. {Equiangular spiral},a plane curve which cuts all its generatrices at the same angle. Same as {Logarithmic spiral}, under {Logarithmic}. {Spiral of Archimedes}, a spiral the law of which is that the generatrix moves uniformly along the revolving line, which also moves uniformly.