complementary

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.”

2. Of the specific pairings of the bases in DNA and RNA.
3. 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.

   “the hands of the most skilful and cunning complementaries alive”

3. An angle which adds with another to equal 90 degrees.