[noun] either one of two chromatic colors that when mixed together give white (in the case of lights) or gray (in the case of pigments); "yellow and blue are complementaries" Synonyms:color
[adjective] acting as or providing a complement (something that completes the whole) Synonyms:complemental, completing
[adjective] of words or propositions so related that each is the negation of the other; "`male' and `female' are complementary terms"
[adjective] of or relating to or suggestive of complementation; "interchangeable electric outlets" Synonyms:interchangeable, reciprocal