Reciprocal

Reciprocal may refer to:

In mathematics

 * Multiplicative inverse, in  mathematics, the number 1/x, which multiplied by x gives the product 1, also known as a reciprocal
 * Reciprocal polynomial, a polynomial obtained from another polynomial by reversing its coefficients
 * Reciprocal rule, a technique in calculus for calculating derivatives of reciprocal functions
 * Reciprocal spiral, a plane curve
 * Reciprocal averaging, a statistical technique for aggregating categorical data

In science and technology

 * Reciprocal aircraft heading, 180 degrees (the opposite direction) from a stated heading
 * Reciprocal lattice, a basis for the dual space of covectors, in crystallography
 * Reciprocal length, a measurement used in science
 * Reciprocating engine or piston engine
 * Reciprocating oscillation in physical wave theory

Life sciences and medicine

 * Hybrid (biology), in genetics, the result of a reciprocal pair of crossings, forming reciprocal hybrids
 * Reciprocal altruism, a form of symbiotic relationship in evolutionary biology
 * Reciprocal cross, a breeding experiment in genetics
 * Sherrington's law of reciprocal innervation in the theory of muscle activation

Social sciences

 * Reciprocal determinism, a theory in psychology

Linguistics

 * Reciprocal construction, a construction in which agent and patient are in a mutual relationship

In reciprocal relationships

 * Reciprocal license, a type of software licenses also known as copyleft
 * Reciprocal link between two web pages
 * Reciprocal obligation, in law, a type of agreement between two individuals
 * Reciprocal Public License (RPL), a software license