conscientious

Etymology

It is borrowed from Middle French consciencieux (“having a sensitive conscience”), recorded in Middle French in 1527,^[2][3][4] from Medieval Latin cōnscientiōsus (“scrupulous; relating to conscience”),^[2][4][5][6] formed from cōnscientia (“conscience”) and -ōsus.^[2][6] Etymonline, Klein and the American Heritage Dictionary give the older French spelling conscientieux.^[7][5][8] The Latin noun is from the present participle of cōnsciō (“to be aware, to be conscious of wrong”), from com- and sciō (“to know”).^[7] The OED compares the slightly earlier English adjectives consciential and conscionable.^[2]

Earliest recorded meaning

Of or relating to conscience; done according to conscience, scrupulous: 1603, in Florio's translation of Montaigne's Essays.^[2][6] Etymonline dates the word to the 1610s.^[7]

Semantic evolution

Of a person, "governed by conscience" is recorded from 1611, in Cotgrave's dictionary,^[2] and Etymonline dates the sense of conduct "regulated by conscience" to the 1630s.^[7] Johnson (1755) defined it as "scrupulous; exactly just; regulated by conscience".^[9] It is now used above all for careful and diligent, the first sense in Collins.^[10] Conscientious objector is recorded in the OED from 1825;^[2] Etymonline dates it to 1896, when it referred to people with religious objections to compulsory vaccination, and the military sense took over during the First World War, with the slang clipping conchy from 1917.^[7] The OED also records conscientious with of or that for "conscious, aware" from 1637.^[2]

Timeline

• 1603 – done according to conscience; scrupulous, in Florio.^[2][6]
• 1611 – of a person, governed by conscience, in Cotgrave.^[2] Etymonline dates this sense to the 1610s.^[7]
• 1636 – binding on the conscience (obsolete).^[2]
• 1637 – conscious, aware.^[2]
• 1825 – conscientious objector.^[2] Etymonline dates it from 1896.^[7]
• 1917 – the clipping conchy.^[7]

Meanings

Adjective

1. Guided by one's conscience; scrupulous and honest: a conscientious judge.^[6][10][2]
2. Taking great care; painstaking and diligent: He is a conscientious student who checks every answer.^[10][6]

Word family

• conscientiously
• conscientiousness
• hyperconscientious
• nonconscientious
• overconscientious
• unconscientious
• conscientious objection
• conscientious objector

Related words

• conscience
• conscious
• science

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
4. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
6. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
9. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
10. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins