complementary

Etymology

It is formed from English complement + -ary,^[2][3][4] and the Shorter Oxford takes it from complemental with the same suffix.^[5] The OED compares French complémentaire, from which Merriam-Webster Unabridged derives the modern word.^[2][6] complement is from Latin complēmentum (“that which fills up or completes”), from compleō (“to fill up”), the source of complete.^[2][3][7]

Earliest recorded meaning

As a noun, "a master of accomplishments": 1616, in Jonson's Cynthia's Revels.^[2] As an adjective, ceremonious or full of compliments: 1628, in J. Earle's Micro-cosmography,^[2] the 1620s in Etymonline.^[3]

Semantic evolution

The early senses belong to complement in its old meaning of courtesy and ceremony, which from about 1655 to 1725 was taken over by the French-derived compliment;^[2] the sense "ceremonious" died out after 1657, and Etymonline notes that it now goes with the other spelling.^[2][3] The modern sense, forming a complement or completing each other, Etymonline finds by 1794, of the French Revolutionary calendar,^[3] and the OED from 1835, with "mutually completing" from 1860.^[2] In science it took fixed uses: complementary colours, which together give white light (by 1814 in Etymonline, 1829 in the OED), and complementary angles, which make a right angle (1829);^[3][2] in mathematics (1841), and in linguistics, complementary distribution (1934).^[2] Complementary medicine, treatments offered beside orthodox medicine, is recorded from 1981.^[2]

Timeline

• 1616 – noun, a master of accomplishments (obsolete).^[2]
• 1628 – ceremonious (obsolete by 1657).^[2]
• 1794 – forming a complement, of the French Revolutionary calendar.^[3]
• 1829 – complementary angles and complementary colours.^[2]
• 1835 – forming a complement, completing.^[2]
• 1860 – of two things, completing each other.^[2]
• c. 1865 – noun, a complementary colour.^[2]
• 1934 – linguistics, complementary distribution.^[2]
• 1981 – complementary medicine.^[2]

Meanings

Adjective

1. Completing something, or of two or more things, making up for each other's lacks so as to form a balanced whole: The two partners have complementary skills.^[8][6][2]
2. Of two angles, adding up to 90 degrees.^[5][2]
3. Of colours, producing white or grey when combined.^[2][6]
4. Relating to complementary medicine, treatment used alongside orthodox medicine.^[8][2]
5. (mathematics, logic) Of two sets, mutually exclusive and together covering every case.^[8]
6. (obsolete, 1628–1657) Ceremonious.^[2][5]

Noun

1. Something in a complementary relation to another, especially a complementary colour.^[6][2]

Word family

• complementarily
• complementariness
• complementarity
• complementary distribution
• complementary angles
• complementary medicine

Related words

• complemental
• complement
• complete
• compliment
• complimentary

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
5. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
6. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins