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

The occasion and the opening were both were momentous. —Greg Cote, Miami Herald, 9 June 2024

With the most serious cases of federal election fraud and classified documents cases still awaiting trial, voters have the momentous decision to hold Trump accountable, allowing the criminal justice system to lock him up, or electing him for four more years. —Letters To The Editor, The Mercury News, 3 June 2024

While opposition parties hailed the outcome as a momentous breakthrough for a country struggling with deep poverty and inequality, the ANC remained the biggest party by some way. —Alicia Adamczyk, Fortune, 1 June 2024

None is more momentous than the recent incorporation of statistics from several different Negro leagues into official Major League Baseball statistics, where, for example, Josh Gibson replaces Ty Cobb for highest batting average of all time. —Jonathan Abrams, New York Times, 1 June 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