vacillate

Etymology

It is borrowed from Latin vacillātus, the past participle of vacillō (“to sway to and fro; to waver, hesitate”),^[2][3][4] and the OED and Hoad cite the participial stem vacillāt-.^[5][6] The same Latin verb gave French vaciller (1314), Italian vacillare, Portuguese vacillar and Spanish vacilar.^[5] Barnhart prefers to take the English verb as probably a back-formation from vacillation, perhaps influenced by Middle French vaciller.^[7] The Latin verb has no good etymology according to de Vaan,^[8] and Etymonline and Barnhart call it of uncertain origin.^[2][7] Barnhart and Klein connect it with a root meaning "to be bent", Proto-Indo-European *wāk-,^[7][9] and Klein compares convexus (“vaulted, arched”).^[9] Merriam-Webster Unabridged compares Middle Irish feccaid (“he kneels”) and a Sanskrit verb meaning "he goes crooked".^[3]

Earliest recorded meaning

To sway unsteadily, to stagger: 1597, according to Barnhart and Merriam-Webster Unabridged.^[7][3] The OED's first quotation is of 1598, in A. M.'s translation of Guillemeau's Frenche Chirurgerye.^[5] Etymonline has the 1590s.^[2]

Semantic evolution

The Latin verb already meant both to sway and to waver: Weekley quotes an old gloss, "to wagge or waver, to be lewse".^[10] The noun vacillation was used of opinion or conduct from about 1400, and of swaying only from 1633,^[5][2] while the verb was first physical and turned to wavering between opinions or courses of action in 1623, in Cockeram's dictionary,^[5][7][2] a meaning Barnhart takes from the noun.^[7] The construction with between is recorded from 1827, in J. F. Cooper's The Prairie.^[5] The word then spread to things that merely vary or fluctuate, from 1835.^[5] The physical sense has receded: the American Heritage Dictionary labels it archaic,^[11] and the wavering of the mind comes first in its entry and in Collins.^[11][12] A rare adjective vacillate, "unsteady", is recorded in 1830.^[5]

Timeline

• 1597 – to sway unsteadily.^[7][3] The OED's first quotation is of 1598.^[5]
• 1623 – to waver between opinions or courses of action.^[5][7]
• 1827 – with between.^[5]
• 1830 – adjective, vacillating, unsteady.^[5]
• 1835 – to fluctuate, to produce varying results.^[5]
• 1841 – to vary, to hover doubtfully.^[5]

Meanings

Verb

1. To waver in one's mind or opinions; to be unable to choose: He vacillated for weeks over which job to take.^[12][11][3]
2. To change back and forth between states; to fluctuate or oscillate: Prices vacillated between high and low all year.^[11][3][5]
3. To sway unsteadily from side to side; to totter or stagger.^[12][3][5] The American Heritage Dictionary labels this use archaic.^[11]

Word family

• vacillatingly
• vacillation
• vacillator

Related words

• vacillant
• vacillating
• vacillatory

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
5. ^ 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
6. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
7. ^ a b c d e f g h Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
8. ^ de Vaan, Michiel (2008), Etymological Dictionary of Latin and the other Italic Languages, Leiden Indo-European Etymological Dictionary Series 7, Leiden; Boston: Brill
9. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
10. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
11. ^ a b c d e The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
12. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins