of great or far-reaching importance or consequence: a momentous day.

Origin of momentous

First recorded in 1645–55; moment + -ous
Related formsmo·men·tous·ly, adverbmo·men·tous·ness, nounun·mo·men·tous, adjectiveun·mo·men·tous·ly, adverbun·mo·men·tous·ness, noun

Synonyms for momentous

Antonyms for momentous Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for momentously

Historical Examples of momentously

  • He was momentously deciding between the emperor and Hoshiko.

    The Way of the Gods

    John Luther Long

  • It is rather the reawakening of an old temper to which England's history has so often and so momentously given expression.

  • Cantelupe stands up, so momentously that Horsham's gentle flow of speech dries up.


    Granville Barker

  • He always spoke respectfully of Effie, and as if momentously impressed with a sense of duty towards her.

  • Thus arose the momentously important mediæval institutions of the Common Land, owned side by side with private land.

British Dictionary definitions for momentously



of great significance
Derived Formsmomentously, adverbmomentousness, noun
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

Word Origin and History for momentously



1650s, from moment + -ous to carry the sense of "important" while momentary kept the meaning "of an instant of time." Related: Momentously; momentousness.

Online Etymology Dictionary, © 2010 Douglas Harper