Complement may refer to:

The arts

* Complement (music), an interval that, when added to another, spans an octave ** Complement (music)#Aggregate complementation, Aggregate complementation, the separation of pitch-class collections into complementary sets * Complementary color, in the visual arts

Biology and medicine

*Complement system (immunology), a cascade of proteins in the blood that form part of innate immunity *Complementary DNA, DNA reverse transcribed from a mature mRNA template *Complementarity (molecular biology), a property whereby double stranded nucleic acids pair with each other *Complementation (genetics), a test to determine if independent recessive mutant phenotypes are caused by mutations in the same gene or in different genes

Grammar and linguistics

* Complement (linguistics), a word or phrase having a particular syntactic role ** Subject complement, a word or phrase adding to a clause's subject after a linking verb **Object complement, a word or phrase adding to the direct object of a verb phrase. * Phonetic complement * Opposite (semantics)#Complementary antonyms, Complementary, a type of opposite in lexical semantics (sometimes called an antonym)

Mathematics

Algebra

* Complement (group theory) * Complementary subspaces * Orthogonal complement * Schur complement

Algorithms

* Complement (complexity), relating to decision problems and complexity classes * Complement operator (regular expressions) * Method of complements, in computer science ** Radix complement ** Diminished radix complement ** Ones' complement ** Two's complement

Discrete mathematics

* Complement graph ** Self-complementary graph, a graph which is isomorphic to its complement * Complemented lattice

Geometry

* Angular complement, Complement of an angle, the difference between a right angle (90 degrees) and a given angle * Knot complement * Complement of a point, the dilation of a point in the centroid of a given triangle, with ratio −1/2

Logic

* Complement (set theory) * Complementary event in probability * Logical complement * Bitwise complement * Complements in Boolean algebra (logic), boolean algebra

Other uses

* Complementary experiments, in physics * Complement good (economics), a good often consumed together with another good * Ship's complement, the number of persons in a ship's company