complement

noun

1.
a word or phrase used to complete a grammatical construction
2.
a complete number or quantity
3.
number needed to make up a whole force
full complement
Derived from:
complemental
4.
something added to complete or embellish or make perfect
togive accompaniment
Derived from:
complement complemental complementary
5.
one of a series of enzymes in the blood serum that are part of the immune response
6.
either of two parts that mutually complete each other
Derived from:
complemental