Reciprocal may refer to:

In mathematics

Multiplicative inverse In mathematics, a multiplicative inverse or reciprocal for a number ''x'', denoted by 1/''x'' or ''x''−1, is a number which when multiplied by ''x'' yields the multiplicative identity, 1. The multiplicative inverse of a fraction ''a''/''b ...

, 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 In physics, the reciprocal lattice represents the Fourier transform of another lattice (group) (usually a Bravais lattice). In normal usage, the initial lattice (whose transform is represented by the reciprocal lattice) is a periodic spatial fu ...

, a basis for the dual space of covectors, in crystallography *

Reciprocal length Reciprocal length or inverse length is a quantity or measurement used in several branches of science and mathematics. As the reciprocal of length, common units used for this measurement include the reciprocal metre or inverse metre (symbol: m&mi ...

, a measurement used in science *

Reciprocating engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common fea ...

or piston engine * Reciprocating oscillation in physical wave theory

Life sciences and medicine

Hybrid (biology) In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...

, 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