undulate

Etymology

The adjective is borrowed from Latin undulātus (“waved, having a wavy form”),^[2][3][4][5] and the verb, first recorded a few years later, is either a back-formation from undulation or formed from Late Latin undula (“small wave”) with -ate,^[3][6] while the OED derives it from a presumed Latin *undulō.^[2] Merriam-Webster and Klein treat that diminutive as an assumed form rather than a recorded one.^[4][5] The base is Latin unda (“wave”),^[7][3][5] from Proto-Indo-European *wed- (“water; wet”),^[7][6] the base that also gave water, wet and vodka, and Ancient Greek ὕδωρ (húdōr, “water”), the source of hydro-.^[8]

Earliest recorded meaning

Marked with wave-like lines: the adjective is first recorded in Phillips's New World of English Words (1658).^[2][3][4] The verb, to move in waves, follows in 1664, in Henry Power's Experimental Philosophy.^[2][3][4] Etymonline gives the same decades, the 1650s and the 1660s.^[6]

Semantic evolution

English first used the word for appearance, for wavy markings, and then for movement.^[2] The motion sense soon had a transitive use, to make something rise and fall like waves;^[2][6] Johnson (1755) knew only this one, defining the verb as "to drive backward and forward; to make to play as waves".^[9] From 1770 it was transferred to sound,^[2] which is still a sense of rising and falling in volume or pitch.^[7][4] In the 19th century the verb came to be used of anything with a wavy surface or outline, such as a road.^[2][10] The adjective, meanwhile, became chiefly a term of botany and zoology from 1760.^[2][10]

Timeline

• 1658 – adjective, furnished with wave-like markings.^[2][3][4]
• 1664 – verb, to move in waves.^[2][3][4]
• 1669 – transitive, to cause to rise and fall like waves.^[2] Etymonline dates this use to the 1660s.^[6]
• 1730 – transitive, to give a wavy or rippling look to something.^[2]
• 1760 – adjective in botany and zoology, having a wavy edge or surface.^[2]
• 1770 – of sound and the like, to rise and fall.^[2]
• 1813 – to float on waves, also figuratively.^[2]
• 1833 – intransitive, to present a wavy surface or outline.^[2]

Meanings

Verb

1. To move in waves or with a smooth rippling, rising and falling motion: The kelp undulated in the current.^[7][11][4]
2. To have a wavy form or outline: low hills that undulate toward the coast.^[7][11][2]
3. To rise and fall in volume or pitch.^[7][4]
4. To cause to move like waves, or to give a wavy form to.^[11][7][10]

Adjective

1. Having a wavy surface, edge or form, especially of a leaf or other part of a plant or animal.^[11][4][10]

Word family

• undulatory
• undulator
• undulation

Related words

• undulant
• inundate
• redundant
• surround
• abundance

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 q r Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b c d e f g h i j Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b c d e f g The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
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 d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
11. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins