reciprocal

inversely related : opposite

of, constituting, or resulting from paired crosses in which the kind that supplies the male parent of the first cross supplies the female parent of the second cross and vice versa

shared, felt, or shown by both sides

something in a reciprocal relationship to another

either of a pair of numbers (such as 2/3 and 3/2 or 9 and 1/9) whose product is one; broadly : multiplicative, inverse

an element of a mathematical set that when multiplied by a given element yields the identity element —called also reciprocal