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
Anna Marie De La Fuente,
Variety,
26 June 2026
Unfortunately for the 12-year-old North Londoner at the heart of this low-key, low-stakes comedy, the momentous game just happened to coincide with his bar mitzvah.
—
Jon O'Brien,
Vulture,
26 June 2026
There are all sorts of celebrations going on to commemorate this momentous occasion, as well as some tasteful product introductions from American brands.
—
Nancy Olson,
Forbes.com,
26 June 2026
On June 28, Mars in Taurus will meet with Jupiter in Cancer, forming a supportive sextile and momentous synergy that rewards our patience and commitment.
—
Valerie Mesa,
PEOPLE,
26 June 2026
See All Example Sentences for momentous
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Adjective
The film will follow 11 stories that occurred in the wake of the momentous coup d’état in Chile on September 11, 1973.
—
Anna Marie De La Fuente,
Variety,
26 June 2026
Unfortunately for the 12-year-old North Londoner at the heart of this low-key, low-stakes comedy, the momentous game just happened to coincide with his bar mitzvah.
—
Jon O'Brien,
Vulture,
26 June 2026
There are all sorts of celebrations going on to commemorate this momentous occasion, as well as some tasteful product introductions from American brands.
—
Nancy Olson,
Forbes.com,
26 June 2026
On June 28, Mars in Taurus will meet with Jupiter in Cancer, forming a supportive sextile and momentous synergy that rewards our patience and commitment.
—
Valerie Mesa,
PEOPLE,
26 June 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 2 Jul. 2026.
Copy CitationKids Definition
momentous
adjective
mo·men·tous
mō-ˈment-əs
: very important
a momentous decision
momentously
adverb
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