undulation

noun un·du·la·tion \ ˌən-jə-ˈlā-shən , ˌən-dyə- , ˌən-də- \

|Updated on: 11 Jun 2018

Definition of undulation

1 a : a rising and falling in waves

b : a wavelike motion to and fro in a fluid or elastic medium propagated continuously among its particles but with little or no permanent translation of the particles in the direction of the propagation : vibration

2 : the pulsation caused by the vibrating together of two tones not quite in unison

3 : a wavy appearance, outline, or form : waviness

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Recent Examples of undulation from the Web

The rover has measured a few more methane spikes, but the new wrinkle is the undulations in the low background levels — higher in summer than winter.

— kenneth chang, New York Times, "Life on Mars? Rover’s Latest Discovery Puts It ‘On the Table’," 7 June 2018
That’s part of the beauty of the course with natural undulations and multiple ways to get around it.

— drew davison, star-telegram, "For its 50th anniversary, the Byron Nelson golf tournament sets a new course | Fort Worth Star-Telegram," 16 May 2018
Periodic functions are repeating patterns like the undulations of a sine wave in trigonometry.

— kenneth chang, New York Times, "Robert P. Langlands Is Awarded the Abel Prize, a Top Math Honor," 20 Mar. 2018
This was a massive discovery: Astronomers had never before seen the undulations of spacetime—that stuff in which everything in the universe swims.

— sarah scoles, WIRED, "How Fast Can Gravitational Wave Detection Get?," 9 Mar. 2018
An entire flotilla of early whale fossils outlines these changes, such as feet that became paddle-like, spines adapted to up-and-down undulation to swim, and teeth suited to nabbing slippery fish.

— brian switek, Smithsonian, "What’s a Missing Link?," 7 Mar. 2018
Tsunami scientists call the buoy reading an anomaly that reflected the seafloor undulations from the quake.

— zaz hollander, Anchorage Daily News, "The case of the phantom tsunami: Why an Alaska buoy showed a big wave that wasn’t there.," 25 Jan. 2018
The trills with which Tchaikovsky sensuously ends some phrases were matched by the rapid pelvic undulations that can be the most singular of belly dancing’s marvels.

— alastair macaulay, New York Times, "Review: ‘Brooklyn Nutcracker’ Is Simply, Imperfectly Charming," 8 Dec. 2017
No kipukas out here: just mile upon mile of the black undulations formerly known as magma.

— elyse butler, Smithsonian, "Hawaii’s Must-See Lava Flows Are Home to New, Startling Ecosystems," 29 Apr. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'undulation.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.