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 Multiplication, multiplied by ''x'' yields the multiplicative identity, 1. The multiplicative inverse of a ra ...

, 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 Reciprocal lattice is a concept associated with solids with translational symmetry which plays a major role in many areas such as X-ray and electron diffraction as well as the energies of electrons in a solid. It emerges from the Fourier tran ...

, 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, defined as the reciprocal of length. Common units used for this measurement include the reciprocal metre or inverse metre (symbo ...

, a measurement used in science *

Reciprocating engine A reciprocating engine, more often known as a piston engine, is 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 features of al ...

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 varieties, subspecies, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two ...

, 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