Wordnet 3.0
NOUN (1)
1.
an internal-combustion engine in which the crankshaft is turned by pistons moving up and down in cylinders;
The Collaborative International Dictionary of English v.0.48:
Reciprocate \Re*cip"ro*cate\ (r[-e]*s[i^]p"r[-o]*k[=a]t), v. i.
[imp. & p. p. Reciprocated
(r[-e]*s[i^]p"r[-o]*k[=a]`t[e^]d); p. pr. & vb. n.
Reciprocating.] [L. reciprocatus, p. p. of reciprocare. See
Reciprocal.]
To move forward and backward alternately; to recur in
vicissitude; to act interchangeably; to alternate.
[1913 Webster]
One brawny smith the puffing bellows plies,
And draws and blows reciprocating air. --Dryden.
[1913 Webster]
Reciprocating engine, a steam, air, or gas engine, etc., in
which the piston moves back and forth; -- in distinction
from a rotary engine, in which the piston travels
continuously in one direction in a circular path.
Reciprocating motion (Mech.), motion alternately backward
and forward, or up and down, as of a piston rod.
[1913 Webster]
WordNet (r) 3.0 (2006):
reciprocating engine
n 1: an internal-combustion engine in which the crankshaft is
turned by pistons moving up and down in cylinders