Open English Wordnet
Nouns
(n)reciprocalsomething (a term or expression or concept) that has an inverse relation to something else“risk is the reciprocal of safety”
(n)multiplicative inverse, reciprocal(mathematics) one of a pair of numbers whose product is 1: the reciprocal of 2/3 is 3/2; the multiplicative inverse of 7 is 1/7
(n)reciprocal cross, reciprocalhybridization involving a pair of crosses that reverse the sexes associated with each genotype
Adjectives
(a)reciprocal, mutualconcerning each of two or more persons or things; especially given or done in return“reciprocal aid”, “reciprocal trade”, “mutual respect”, “reciprocal privileges at other clubs”
(s)reciprocalof or relating to the multiplicative inverse of a quantity or function“the reciprocal ratio of a:b is b:a”