Complement

Complement of an angle is what it lacks to make up 90°; of an arc, to make up a quadrant; and hence, in Astronomy, the complement of a star is its zenith-distance. In Music, two intervals, which together make up an octave, are called complementary (see INVERSION). In Arithmetic, if any number is subtracted from the next higher power of ten, the result is its complement. Thus 7 and 3 are complementary; so are 63 and 37; 881 and 119; and 1'4384386 is the complement to 8'5615614. In Chromatics, red is the complement of green, orange of blue, and yellow of violet.