complementary

adjective

1. forming a complement; completing.
2. complementing each other.

noun, plural com·ple·men·ta·ries.

3. complementary color(def 1).

adjective

1. acting as or forming a complement; completing
2. forming a satisfactory or balanced whole
3. forming a mathematical complementsine and cosine are complementary functions
4. maths logic (of a pair of sets, etc) mutually exclusive and exhaustive, each being the complement of the other
5. (of genes) producing an effect in association with other genes
6. involving or using the treatments and techniques of complementary medicine