momentous
adjective
mo·men·tous
mō-ˈmen-təs 
mə-
: 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
The new first lady of New York City wore a style from the independent luxury label Miista, specifically the brand’s Shelley boots, for the momentous occasion held in the former city hall subway at midnight.
—Jaden Thompson, Footwear News, 9 Jan. 2026
The crypto industry is hoping to build on its momentous progress in 2026.
—Leo Schwartz, Fortune, 8 Jan. 2026
Don't let it get lost in the shuffle of all the momentous days since.
—Bill Goodykoontz, AZCentral.com, 6 Jan. 2026
Most athletes train for four long years in the hopes of hitting their peak performance on the right day, at just the right time, for a few momentous seconds or minutes.
—Alice Park, Time, 5 Jan. 2026
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Cite this Entry
“Momentous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/momentous. Accessed 20 Jan. 2026.
Kids Definition
momentous
adjective
mo·men·tous
mō-ˈment-əs
: very important
a momentous decision
momentously
adverb
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