complement

noun

1
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
2
either of two parts that mutually complete each other
3
a word or phrase used to complete a grammatical construction
4
number needed to make up a whole force
a full complement of workers
5
a complete number or quantity
a full complement
6
one of a series of enzymes in the blood serum that are part of the immune response

1
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

Also useful for “complement”:Crossword— A long fill for tough grids