adjective Acting as a complement; making up a whole with something else.
I'll provide you with some complementary notes to help you study.
adjective Of the specific pairings of the bases in DNA and RNA.
adjective Pertaining to pairs of properties in quantum mechanics that are inversely related to each other, such as speed and position, or energy and time. (See also Heisenberg uncertainty principle.)
noun A complementary colour.
noun One skilled in compliments.
noun An angle which adds with another to equal ninety degrees.