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

Synonyms

• big
• consequential
• earth-shattering
• earthshaking
• eventful
• historic
• important
• major
• material
• meaningful
• monumental
• much
• significant
• substantial
• tectonic
• weighty

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

Speaking with Good Morning America at the 2024 iHeartRadio Jingle Ball in Los Angeles on Friday, December 6, the 49-year-old TV personality shared his plans for the momentous occasion. —Paul Du Quenoy, Newsweek, 9 Dec. 2024

This year, millions of viewers looked to the sky during a momentous day in April to view a stunning total solar eclipse. —Joe Spring, Smithsonian Magazine, 9 Dec. 2024

The Meaning Behind The Proliferation Of Posts About The End Of The Eras Tour And Taylor Swift For many people online, the end of the Eras Tour is a momentous occasion — and a sad one too. —Callum Booth, Forbes, 9 Dec. 2024

Phelan has also found himself in the crosshairs of Attorney General Ken Paxton after the speaker shepherded a House vote to impeach the three-term Republican — a momentous effort that was derailed in Patrick's Senate. —John C. Moritz, Austin American-Statesman, 6 Dec. 2024

Word History

First Known Use

1631, in the meaning defined above

Kids Definition

momentous

adjective

mo·​men·​tous mō-ˈment-əs 

: very important

a momentous decision

momentously adverb