complement

a word or phrase used to complete a grammatical construction

a complete number or quantity; "a full complement"

number needed to make up a whole force; "a full complement of workers"

something added to complete or embellish or make perfect; "a fine wine is a perfect complement to the dinner"; "wild rice was served as an accompaniment to the main dish"

one of a series of enzymes in the blood serum that are part of the immune response

either of two parts that mutually complete each other

make complete or perfect; supply what is wanting or form the complement to; "I need some pepper to complement the sweet touch in the soup"