mo·​men·​tous mō-ˈmen-təs How to pronounce momentous (audio)
: having great or lasting importance : consequential, significant
a momentous decision
a momentous event/occasion
The Senate begins a momentous debate on health care today …The New York Times
Deydey usually talked about his travels, the places he'd seen and the people, the close calls and momentous encounters with animals, weather, other Anishinabeg, and best of all, ghosts.Louise Erdrich
The late nineteenth century was strewn with inventions. Many were momentous, but few affected men and women more closely than the bicycle and its motorized offspring: motorcycle, motor-car and aeroplane.Eugen Weber
momentously adverb
a momentously important decision
… a … twist that is executed differently from the comic book story, but is just as dramatically and momentously presented. The Philippines Daily Inquirer
momentousness noun
But other East Europeans had little time to marvel at the momentousness of the moment. Just one day after the fall of the [Berlin] Wall, Bulgaria's dour leader of 35 years, Todor Zhivkov, was ousted. Stephen E. Deane

Examples of momentous in a Sentence

My college graduation was a momentous day in my life. a momentous occasion that will go down in the history books
Recent Examples on the Web Some are likening his ouster to Steve Jobs being fired at Apple, a sign of how momentous the shakeup feels amid an AI boom that has rejuvenated Silicon Valley. Bysteve Mollman, Fortune, 19 Nov. 2023 No one wanted to be remembered as the middle manager who failed to keep the internet online on this momentous occasion—the first day that the new bosses were watching. Andy Greenberg, WIRED, 14 Nov. 2023 For Paradis, the complaint comes at a momentous point in his criminal case. Dakota Smith, Los Angeles Times, 6 Nov. 2023 The researchers used computer models to simulate this momentous collision. Will Sullivan, Smithsonian Magazine, 3 Nov. 2023 The momentous Monday morning when Phoebe Philo opens her online shop has finally arrived‚ after surely the longest tease in fashion history. Sarah Mower, Vogue, 30 Oct. 2023 Nuremberg’s tribunal is better known, but the effort to prosecute the Japanese for war crimes was no less momentous. Wsj Books Staff, WSJ, 27 Oct. 2023 That's a momentous event -- a happy thing to normal people. Erin Moriarty, CBS News, 8 Oct. 2023 Ed will be departing at the end of December, marking a momentous occasion for all of us who have had the privilege of working with him and the opportunity to benefit from his wealth of knowledge and his passion for television production. Jennifer Maas, Variety, 30 Oct. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'momentous.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1631, in the meaning defined above

Time Traveler
The first known use of momentous was in 1631

Dictionary Entries Near momentous

Cite this Entry

“Momentous.” Dictionary, Merriam-Webster, Accessed 8 Dec. 2023.

Kids Definition


mo·​men·​tous mō-ˈment-əs How to pronounce momentous (audio)
: very important
a momentous decision
momentously adverb

More from Merriam-Webster on momentous

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!