*reciprocate*

v. i. [ imp. & p. p. Reciprocated 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 ]