'Complementary angles' definitions:

Definition of 'complementary angles'

(from WordNet)
noun
Two angles whose sum is a right angle

Definition of 'Complementary angles'

From: GCIDE
  • Complementary \Com`ple*men"ta*ry\, a. Serving to fill out or to complete; as, complementary numbers. [1913 Webster]
  • Complementary colors. See under Color.
  • Complementary angles (Math.), two angles whose sum is 90[deg]. [1913 Webster]