From The Collaborative International Dictionary of English v.0.48:
Spiral \Spi"ral\, n. [Cf. F. spirale. See Spiral, a.]
1. (Geom.) A plane curve, not reentrant, 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.
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2. Anything which has a spiral form, as a spiral shell.
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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.
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From The Collaborative International Dictionary of English v.0.48:
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.
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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.
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3. (Geom.) Of or pertaining to a spiral; like a spiral.
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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.
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