Reciprocate, v. t.
To give and return mutually; to make return for; to give in return; to unterchange; to alternate; as, to reciprocate favors. Cowper.
1 other Webster entry under this spelling
Reciprocate, v. i. [imp. & p. p. Reciprocated; p. pr. & vb. n. Reciprocating.]
To move forward and backward alternately; to recur in vicissitude; to act interchangeably; to alternate. One brawny smith the puffing bellows plies, And draws and blows reciprocating air. Dryden. 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.
Shades of meaning
Fernald has no entry of its own for reciprocate; he lists it under requite.
He lists it without comment; the entries above explain its neighbors.