complementary

Etymology

complement + -ary

adj

1. Acting as a complement; making up a whole with something else.
   I'll provide you with some complementary notes to help you study.
   The two business partners had complementary abilities: one had excellent people skills, while the other had a head for figures.
   Using the terminology we introduced earlier, we might then say that black and white squares are in complementary distribution on a chessboard. By this we mean two things: firstly, black squares and white squares occupy different positions on the board: and secondly, the black and white squares complement each other in the sense that the black squares together with the white squares comprise the total set of 64 squares found on the board (i.e. there is no square on the board which is not either black or white). 1988, Andrew Radford, Transformational grammar: a first course, Cambridge, UK: Cambridge University Press, page 140
2. (genetics) Of the specific pairings of the bases in DNA and RNA.
3. (physics) 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

1. A complementary colour.
2. (obsolete) One skilled in compliments.
3. An angle which adds with another to equal 90 degrees.