zealous

Etymology

It is borrowed from Medieval Latin zēlōsus (“ardent, fervent; full of zeal”),^[2][3][4][5] recorded from the 5th or 6th century of an emotion, and of a group of people since the 7th.^[2] The Latin adjective is formed from zēlus (“zeal”) and the suffix -ōsus,^[2][4] and zēlus is from Ancient Greek ζῆλος (zêlos, “jealousy, fervour, zeal”),^[5] which Klein thinks is probably related to ζητέω (zētéō, “I seek for”).^[5] The Medieval Latin word is also the source of zeloso and celoso.^[3] Klein calls jealous a doublet of the word; it has the same source, came through French and is recorded earlier.^[5][3][2]

Earliest recorded meaning

Marked by passionate enthusiasm for a cause or belief, said of an action or thing: about 1495, in a sermon by R. Fitzjames.^[2] Of a person, it is first recorded in 1526, in Tyndale's Bible (Acts 21:20).^[2][4] Etymonline dates the word to the 1520s,^[3] and Dictionary.com to 1520–30.^[6]

Semantic evolution

The word came into a language that already had its doublet: Etymonline notes that the sense "fervent, inspired" was found earlier in jealous, from the late 14th century.^[3] Tyndale's first use of a person introduces the object of the zeal with for or of, a construction the OED now calls somewhat rare.^[2] From 1531 it could take an infinitive or clause stating the goal, and by 1545 it was used with no construction at all.^[2] It also overlapped with jealous in another way: from 1545, chiefly of God, it could mean fiercely protective, a use the OED says followed jealous and is now rare.^[2] From 1582 to 1641 it could describe intense emotion in general, such as righteous anger.^[2] Johnson (1755) defined it simply as "ardently passionate in any cause".^[7]

Timeline

• c. 1495 – of an action or thing, marked by passionate enthusiasm.^[2]
• 1526 – of a person, devoted to a cause, with for or of.^[2][4]
• 1531 – with an infinitive or clause stating the goal.^[2]
• 1545 – fiercely protective, chiefly of God; also of a person, with no construction.^[2]
• 1582 – marked by intense or righteous emotion (obsolete by 1641).^[2]

Meanings

Adjective

1. Full of intense enthusiasm for a person, cause or belief; ardent or fervent: a zealous defender of the town's old library.^[8][4]
2. Showing such enthusiasm, said of an action or thing: their zealous efforts to save the marsh.^[2][4]

Word family

• zealously
• zealousness
• nonzealous
• overzealous
• superzealous
• unzealous

Related words

• jealous
• zeal
• zealot
• zealotry

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 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 f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c d Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
7. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
8. ^ Collins English Dictionary (2023), Glasgow: HarperCollins