COMPLEMENT

In many different fields, the 'complement' of ''X'' is something that together with ''X'' makes a complete whole, something that supplies what ''X'' lacks.
'Complement' may refer to:

★ complement, the number of persons in a ship's full company, including both commissioned officers and crew

★ complement, binary representations of negative values in computer science

★
★ ones' complement

★
★ two's complement

★ complement (complexity), relating to decision problems and complexity classes

★ complement good, a good often consumed together with another good in economics

★ complement (linguistics), a word or phrase having a particular syntactic role

★ complement (mathematics) has many meanings - see this disambiguation page

★ complement (music), an interval that when added to another spans an octave

★ complementary color, in painting and optics

★ complementary experiments, in physics

★ method of complements, a method to compute addition and subtraction in computer science

★ phonetic complement
;Biology

★ complement system, 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