Complement may refer to:
The arts
- Complement (music), an interval that, when added to another, spans an octave
- 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
- Phonetic complement
- Complementary, a type of opposite in lexical semantics (sometimes called an antonym)
Mathematics
Algebra
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
- 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
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