adj. & n.
1. in return (offered a reciprocal greeting).
2 mutual (their feelings are reciprocal).
3 Gram. (of a pronoun) expressing mutual action or relation (as in each other).
4 inversely correspondent; complementary (natural kindness matched by a reciprocal severity).
--n. Math. an expression or function so related to another that their product is unity (1/2 is the reciprocal of 2).
reciprocality n. reciprocally adv.
Etymology: L reciprocus ult. f. re- back + pro forward