• synonyms


[kom-pluh-men-tuh-ree, -tree]
  1. forming a complement; completing.
  2. complementing each other.
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noun, plural com·ple·men·ta·ries.
  1. complementary color(def 1).
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Origin of complementary

First recorded in 1590–1600; complement + -ary
Related formscom·ple·men·ta·ri·ness, nounun·com·ple·men·ta·ry, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for complementariness



  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
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Derived Formscomplementarily or complementally, adverbcomplementariness, 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

Word Origin and History for complementariness



1620s, "ceremonious," from complement + -ary. Sense "forming a complement" attested from 1829, earliest in complementary colors.

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Online Etymology Dictionary, © 2010 Douglas Harper