- The definition of momentous is an important moment or something important.
An example of momentous as an adjective is a momentous wedding, an important event in someones life.
momentous definition by Webster's New World
of great moment; very important: a momentous decision
momentous definition by American Heritage Dictionary
Of utmost importance; of outstanding significance or consequence: a momentous occasion; a momentous decision.
- mo·menˈtous·ly adverb
- mo·menˈtous·ness noun