unitary

Etymology

It is formed from English unit + -ary, and partly from the stem of unity,^[2][3][4][5] and in many senses it follows French unitaire.^[2] The noun unit is an alteration of unity, which is from Anglo-Norman unite, from Latin ūnitās (“oneness”), from ūnus (“one”).^[6]

Earliest recorded meaning

In philosophy and theology, relating to or based on unity: about 1790, in J. Stewart's Revolution of Reason.^[2] Etymonline and Merriam-Webster date the word to 1847, Dictionary.com to 1810–20.^[6][3][5]

Semantic evolution

From 1803 the word meant having the nature of a unit, indivisible,^[2] and since 1833 serving as a unit of measurement.^[2][6] The political sense, a system in which power rests with a central government rather than with its parts, is recorded from 1822 and follows the French constitution unitaire;^[2] in Britain it was later applied to a single tier of local government, the unitary authority (1936).^[2] Scientific uses followed: in chemistry a notation treating molecules as whole units (1855), and in mathematics, from 1891, a kind of matrix.^[2] The French adjective was also used from 1721 for anti-Trinitarian beliefs, which English names with Unitarian.^[2]

Timeline

• c. 1790 – based on or characterized by unity.^[2]
• 1803 – having the nature of a unit; indivisible.^[2]
• 1810 – crystallography, of a crystal form in Haüy's theory (now obsolete).^[2]
• 1822 – of a system of government with power held centrally.^[2]
• 1833 – serving as a unit of measurement.^[2]
• 1846 – of an alphabet, with one letter for each sound.^[2]
• 1891 – mathematics, of a matrix.^[2]
• 1936 – British, of a single-tier local authority.^[2]

Meanings

Adjective

1. Of, relating to or based on unity; forming a single whole: a unitary view of mind and body.^[3][7][2]
2. Of or relating to a unit; having the nature of a unit, not divided.^[8][3][7]
3. Of a system of government in which power is held by a central authority, as opposed to a federal one.^[3][7][2]
4. (chiefly British) Of a single-tier body of local government: a unitary authority.^[2]
5. (mathematics) Of a matrix or operator of a particular kind.^[2]

Word family

• unitarily
• unitariness

Related words

• unitarian
• unitize
• unit
• unity
• one
• unique

References

1. ^ 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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins
8. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt