The Collaborative International Dictionary of English v.0.48:
Lever \Le"ver\ (l[=e]"v[~e]r or l[e^]v"[~e]r; 277), n. [OE.
levour, OF. leveor, prop., a lifter, fr. F. lever to raise,
L. levare; akin to levis light in weight, E. levity, and
perh. to E. light not heavy: cf. F. levier. Cf. Alleviate,
Elevate, Leaven, Legerdemain, Levee, Levy, n.]
1. (Mech.) A rigid piece which is capable of turning about
one point, or axis (the fulcrum), and in which are two or
more other points where forces are applied; -- used for
transmitting and modifying force and motion. Specif., a
bar of metal, wood, or other rigid substance, used to
exert a pressure, or sustain a weight, at one point of its
length, by receiving a force or power at a second, and
turning at a third on a fixed point called a fulcrum. It
is usually named as the first of the six mechanical
powers, and is of three kinds, according as either the
fulcrum F, the weight W, or the power P, respectively, is
situated between the other two, as in the figures.
(a) A bar, as a capstan bar, applied to a rotatory piece
to turn it.
(b) An arm on a rock shaft, to give motion to the shaft or
to obtain motion from it.
Compound lever, a machine consisting of two or more levers
acting upon each other.
Lever escapement. See Escapement.
Lever jack. See Jack, n., 5.
Lever watch, a watch having a vibrating lever to connect
the action of the escape wheel with that of the balance.
Universal lever, a machine formed by a combination of a
lever with the wheel and axle, in such a manner as to
convert the reciprocating motion of the lever into a
continued rectilinear motion of some body to which the
power is applied.