coherent

Etymology

It is borrowed from Middle French cohérent,^{[2][3][4][5][6]} from Latin cohaerēns (“sticking together”), the present participle of cohaereō (“to cling together”),^[2][3][4][6] formed from co- (“together”), the assimilated form of com, and haereō (“to stick, cling”).^[3][7][8] The Shorter Oxford and the Oxford Dictionary of English take it directly from the Latin participle,^[9][10] and Dictionary.com from a Medieval Latin variant cohērēns.^[11] The verb cohere was borrowed from Latin a little later, in 1598.^[2][4]

Earliest recorded meaning

Logically related to something, or in harmony with it: about 1555 in Merriam-Webster and Barnhart,^[5][4] in the 1550s in Etymonline, which glosses it as "harmonious".^[3] The OED's first record of this sense, now obsolete, is in Harpsfield's Treatise on Divorce (before 1575).^[2][9]

Semantic evolution

The physical sense, sticking firmly together, is recorded from 1578.^[2] From 1580, in North's translation of Plutarch, the word was used of thought or speech whose parts are consistent and hang together;^[2][3] it was applied to non-material bonds from 1656 and to persons from 1725, in Watts's Logick.^[2] Johnson (1755) gave three senses: sticking together so as to resist separation; suitable to something else, with a quotation from Shakespeare's All's Well That Ends Well; and consistent, not contradicting itself, quoting Watts's "a coherent thinker".^[12] The botanical use, united by cohesion, dates from 1830, and specialized senses in physics from 1902, in a translation of Drude's Theory of Optics;^[2] today the word describes waves that have the same phase or a fixed phase difference, as in coherent light.^[13][5] A noun coherent, one who coheres with others, appears in Florio's dictionary of 1598.^[2]

Timeline

• c. 1555 – logically related, in harmony.^[5][4]
• before 1575 – related logically; accordant (obsolete by 1616).^[2]
• 1578 – sticking firmly together.^[2]
• 1580 – of thought or speech, consistent, hanging together.^[2]
• 1598 – noun, one who coheres with others.^[2]
• 1656 – of non-material cohesion.^[2]
• 1725 – of persons, thinking or speaking consistently.^[2]
• 1830 – in botany, united by cohesion.^[2]
• 1902 – in physics.^[2]

Meanings

Adjective

1. Logical and consistent, with all its parts fitting together clearly: The committee never produced a coherent strategy.^[13][5][2]
2. Of a person, able to speak or think clearly and logically: After the accident he was barely coherent.^[13][2]
3. Sticking or holding firmly together; cohering.^[13][5][2]
4. In physics, of two or more waves, having the same phase or a fixed phase difference, as in coherent light.^[13][5][2]
5. Of a system of units, made up only of units whose product or quotient gives the unit of the resulting quantity.^[13]
6. In botany, united by cohesion.^[5][2]
7. (obsolete, before 1575–1616) Logically related; accordant or in harmony with something.^[2][9][12]

Word family

• coherently
• noncoherent
• coherent light

Related words

• adherent
• coherence
• cohere
• cohesive
• inherent
• adhere
• inhere
• hesitate

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
5. ^ a b c d e f g h Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
9. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
10. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
11. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
12. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
13. ^ a b c d e f Collins English Dictionary (2023), Glasgow: HarperCollins