(number theory) The mathematical theorem which states that, for given odd prime numbers p and q, the question of whether p is a square modulo q is equivalent to the question of whether q is a square modulo p.

(grammar) A pronoun referring to an antecedent in the plural, and expressing a mutual relation.

plural of ethic of reciprocity

plural of reciprocating saw

(biology) The phenomenon of two organisms acting in ways that mutually benefit one another.

(ethics) The golden rule used by philosophers.

(number theory, recreational mathematics) A magic square using the decimal digits of the reciprocal of a prime number.

plural of prime reciprocal magic square