[ kom-pluh-men-tuh-ree, -tree ]
See synonyms for complementary on
  1. forming a complement; completing.

  2. complementing each other.

noun,plural com·ple·men·ta·ries.

Origin of complementary

First recorded in 1590–1600; complement + -ary

Other words from complementary

  • com·ple·men·ta·ri·ness, noun
  • un·com·ple·men·ta·ry, adjective

Words Nearby complementary Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use complementary in a sentence

British Dictionary definitions for complementary



/ (ˌkɒmplɪˈmɛntərɪ, -trɪ) /

  1. acting as or forming a complement; completing

  2. forming a satisfactory or balanced whole

  1. forming a mathematical complement: sine and cosine are complementary functions

  2. maths logic (of a pair of sets, etc) mutually exclusive and exhaustive, each being the complement of the other

  3. (of genes) producing an effect in association with other genes

  4. involving or using the treatments and techniques of complementary medicine

Derived forms of complementary

  • complementarily or complementally, adverb
  • complementariness, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012