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momentous

American  
[moh-men-tuhs] / moʊˈmɛn təs /

adjective

  1. of great or far-reaching importance or consequence.

    a momentous day.
    Synonyms:
    serious, crucial, critical, vital
    Antonyms:
    trifling, trivial
momentous British  
/ məʊˈmɛntəs /

adjective

  1. of great significance

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Related Words

See heavy.

Other Word Forms

  • momentously adverb
  • momentousness noun
  • unmomentous adjective
  • unmomentously adverb
  • unmomentousness noun

Etymology

Origin of momentous

First recorded in 1645–55; moment + -ous

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.