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

Example Sentences

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 Netflix is taking to the upfront at a momentous time. Brian Steinberg, Variety, 17 May 2023 In what amounts to a rather momentous retcon, the corrupt-politician heavy of Fast Five actually had a son standing perpetually off camera: a sociopathic rich kid named Dante (Jason Momoa), who's now out for revenge on the chrome-domed muscle man who car-crashed his daddy. A.a. Dowd, Chron, 17 May 2023 Three-quarters of a century later, the decision looms as momentous. Gordon F. Sander, Washington Post, 13 May 2023 But ours were on a pair of comfy sneakers that Kate Middleton whipped out during the momentous weekend. Alyssa Grabinski, Peoplemag, 12 May 2023 While attuned to the momentous effects of climate, a project like this could point in several different directions. Ben Ehrenreich, The New Republic, 10 May 2023 Since that momentous day in 1994, it’s become a tradition for my mom and me to spend our birthdays together. Kailyn Brown, Los Angeles Times, 10 May 2023 Coming at the end of a two-year-process, the momentous proposal is the first state-level attempt to grapple with the lingering effects of slavery and racist laws. Irina Ivanova, CBS News, 8 May 2023 This morning, the United Kingdom's new sovereign was crowned next to his wife, Queen Camilla, in a momentous ceremony at Westminster Abbey. Quinci Legardye, Harper's BAZAAR, 8 May 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 4 Jun. 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

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