Merriam-Webster's Word of the Day for December 11, 2025 is:

leviathan • \luh-VYE-uh-thun\  • noun

Leviathan is a word with literary flair that can refer broadly to something very large and powerful, or more narrowly to a large sea animal, or a totalitarian state having a vast bureaucracy.

// Towering leviathans of the forest, giant sequoias often reach heights of more than 200 feet.

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Examples:

“These are dim days for the leviathan merchants. The smart whaling families have diversified and will hang onto their wealth for years to come. ... The less smart, those convulsed by the strange desire to continue doing what had always been done, who consider it a divinely issued directive to rid the waves of great fish, now face a problem: the Atlantic whale that built their houses and ships has seemingly wised up ...” — Ethan Rutherford, North Sun, or The Voyage of the Whaleship Esther: A Novel, 2025

Did you know?

Old Testament references to a huge sea monster, Leviathan (in Hebrew, Liwyāthān), are thought to have been inspired by an ancient myth in which the god Baal slays a multiheaded sea monster. Leviathan appears in the Book of Psalms as a sea serpent that is killed by God and then given as food to creatures in the wilderness, and it is mentioned in the Book of Job as well. After making a splash in English in the 1300s, the word Leviathan began to be used, capitalized and uncapitalized, for enormous sea creatures both imagined and real—including as a synonym of whale over 100 times in Herman Melville’s Moby-Dick, as in “ere the Pequod’s weedy hull rolls side by side with the barnacled hulls of the leviathan.” Today, leviathan can be used for anything large and powerful, from ships to corporations.