Etymologically
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tertiary

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Pronunciation

  • UK: /ˈtɜː.ʃi.ə.ɹiː/, /ˈtɜː.ʃə.ɹiː/[1]
  • US: /ˈtɝ.ʃiˌɛɹ.i/, /ˈtɝ.ʃə.ɹi/[1]

Etymology

It is borrowed from Latin tertiārius (“of the third part or rank”),[2][3][4][5][6][7][8] formed from tertius (“third”) with the suffix -ārius, English -ary.[9][5][6][2] The Latin ordinal is from the root of trēs (“three”),[7] and is related to third and three.[3][10][11][7] For the noun meaning a member of a Third Order, Merriam-Webster gives Medieval Latin tertiārius as the source.[5] The OED compares French tertiaire.[2] The geological sense follows Italian terziari, used in 1760 by the Italian geologist Giovanni Arduino,[7] and was so named because the preceding era was then called “Secondary”.[10][7]

Earliest recorded meaning

As a noun, a member of the Third Order of a monastic body: about 1540.[2][12][6][5] The adjective, "of the third order, rank or degree", is first recorded in 1656, in Blount's Glossographia;[2][3][5] Dictionary.com dates the word to 1540–50.[9]

Semantic evolution

In 1794 early geologists applied tertiary to the mountains of the most recent formation,[2][7] part of an early division of rocks into Primary, Secondary and Tertiary; in England it first meant, vaguely, the formations above the Chalk.[7] Weekley dates the geological sense to the 18th century,[13] and the Tertiary as the period between the Mesozoic and the Quaternary was established in the 19th century.[6][7] Many technical senses arose in the 19th and 20th centuries: in surveying (1851), in chemistry for compounds and carbon atoms (1854, 1872, 1903), for the innermost wing feathers of birds (1834) and for colours mixed from secondary ones (1848).[2][12] In the 20th century the word was applied to particles in physics (1938), to service industries in economics (1940), to the folding of protein molecules (1952), to tertiary education after secondary school (1961) and to advanced methods of oil recovery (1975).[2]

Timeline

  • c. 1540 – noun, a member of a Third Order.[2][12]
  • 1656 – of the third order or rank.[2][3]
  • 1794 – in geology.[2][7]
  • 1834 – noun, a tertiary feather.[12]
  • 1848 – of a colour mixed from secondary colours.[12]
  • 1854 – in chemistry.[2]
  • 1940 – of service industries.[2]
  • 1952 – of the folding of protein molecules.[2]
  • 1961 – tertiary education.[2]

Meanings

Adjective

  1. Third in order, rank, degree or importance: a tertiary consideration.[14][5][2]
  2. Of education, following secondary school, as at a university or college.[14][2]
  3. Of an industry, providing services rather than extracting raw materials or manufacturing goods.[14][2]
  4. (geology, Tertiary) Of the first period of the Cenozoic era, before the Quaternary.[14][6][7]
  5. (chemistry) Of a compound or carbon atom, having the characteristic group on a carbon atom that is bonded to three other carbon atoms.[2][6]
  6. (biochemistry) Of the three-dimensional folding of a protein or other large molecule.[2]

Noun

  1. A lay member of a Third Order of a monastic body.[5][6][2][10]
  2. (the Tertiary) The Tertiary period, or its rocks.[14][6]
  3. One of the innermost wing feathers of a bird.[6][12]
  4. A colour made by mixing a primary and a secondary colour.[6][12]

Word family

  • tertiary color
  • tertiary care

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  4. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  5. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  6. ^ a b c d e f g h i j Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  7. ^ a b c d e f g h i j Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  9. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  10. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  11. ^ Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
  12. ^ a b c d e f g Kay, Christian; Roberts, Jane; Samuels, Michael; Wotherspoon, Irené, eds. (2009), Historical Thesaurus of the Oxford English Dictionary, Oxford: Oxford University Press; online edition (2024)
  13. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
  14. ^ a b c d e Collins English Dictionary (2023), Glasgow: HarperCollins