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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