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
The New York TimesDeydey 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
Louise ErdrichThe 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
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
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
Stephen E. Deane
mo·men·tous·ness
plural -es
: the quality or state of being momentous
impress his visitors with the momentousness … of all he had to say—H. V. Gregory
H. V. GregoryExamples of momentous in a Sentence
Adjective
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
Gary Bedore,
Kansas City Star,
3 July 2026
At the time, this seemed like the more momentous day, as John Adams wrote in a letter to his wife Abigail on July 3.
—
Harmeet Kaur,
CNN Money,
3 July 2026
The royal gradually resumed royal duties last year and made a momentous appearance at Wimbledon's men's singles final in July 2024, in what marked a rare public outing during her cancer treatment.
—
Janine Henni,
PEOPLE,
2 July 2026
Hall, a Republican from Weatherford, said the momentous achievement wouldn’t have been possible had the Lord not paved the way.
—
Rachel Royster
july 2,
Fort Worth Star-Telegram,
2 July 2026
See All Example Sentences for momentous
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Adjective
That momentous draw came in the final group-stage game of the prestigious tournament.
—
Gary Bedore,
Kansas City Star,
3 July 2026
At the time, this seemed like the more momentous day, as John Adams wrote in a letter to his wife Abigail on July 3.
—
Harmeet Kaur,
CNN Money,
3 July 2026
The royal gradually resumed royal duties last year and made a momentous appearance at Wimbledon's men's singles final in July 2024, in what marked a rare public outing during her cancer treatment.
—
Janine Henni,
PEOPLE,
2 July 2026
Hall, a Republican from Weatherford, said the momentous achievement wouldn’t have been possible had the Lord not paved the way.
—
Rachel Royster
july 2,
Fort Worth Star-Telegram,
2 July 2026
See All Example Sentences for momentous
Cite this Entry
“Momentous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/momentous. Accessed 4 Jul. 2026.
Copy CitationKids Definition
momentous
adjective
mo·men·tous
mō-ˈment-əs
: very important
a momentous decision
momentously
adverb
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