complement

com·ple·ment

noun \ˈkäm-plə-mənt\

Definition of COMPLEMENT

1

: a group or set (as of chromosomes or DNA) that is typical of the complete organism or one of its parts—see chromosome complement

2

: a complementary color

3

: the thermolabile group of proteins in normal blood serum and plasma that in combination with antibodies causes the destruction especially of particulate antigens (as bacteria and foreign blood corpuscles)