undulate

Merriam-Webster's Word of the Day for March 25, 2026 is: undulate \UN-juh-layt\ verb Undulate is a formal word that means “to move or be shaped like waves.” // On the approach to the tulip festival, visitors are greeted by a large field of the colorful flowers undulating in the wind. [See the entry >](https://www.merriam-webster.com/dictionary/undulate) Examples: “When sufficiently heated, the fresh cheese contracts, sweating whey from the curds that provides liquid to cook the dough, which will plump up and undulate slightly as it expands.” — Karima Moyer-Nocchi, The Epic History of Macaroni and Cheese: From Ancient Rome to Modern America, 2026 Did you know? Undulate and [inundate](https://www.merriam-webster.com/dictionary/inundate) (“to cover something with a flood of water”) are word cousins that flow from unda, the Latin word for “wave.” No surprise there. But would you have guessed that [abound](https://www.merriam-webster.com/dictionary/abound), [surround](https://www.merriam-webster.com/dictionary/surround), and [redound](https://www.merriam-webster.com/dictionary/redound) are also unda offspring? While their modern definitions have nothing to do with waves or water, at some point in their early histories, they all meant “to overflow,” and caught a wave from there.