recíproco

Recíproco is a term used in Spanish and Portuguese meaning mutual or given in return. It functions as both an adjective and, in some contexts, a noun referring to a reciprocal relation or element. The word derives from Latin reciprocus, through the Romance languages.

In mathematics, the reciprocal of a nonzero number a is 1/a. For a square invertible matrix, the reciprocal is its inverse, denoted A^−1. The concept also appears in algebra and calculus in relation to multiplicative inverses and reciprocal polynomials, where the coefficients are reversed.

In linguistics and grammar, recíproco describes mutual actions between participants. Reciprocal constructions express actions performed by two or more subjects upon each other, such as mutual greetings or exchanges. The term is used to analyze how languages encode reciprocity, often with dedicated pronouns, affixes, or verb forms.

In the social sciences and biology, reciprocal altruism refers to behavior that benefits another organism at a cost to the actor with the expectation of future reciprocation. Proposed by Robert Trivers in 1971, it is used to explain cooperation among humans and other animals in environments where exchanges are possible and timing matters.