Wordnet 3.0
ADJECTIVE (1)
1.
of very great significance;
- Example: "deciding to drop the atom bomb was a very big decision"- Example: "a momentous event"
The Collaborative International Dictionary of English v.0.48:
Momentous \Mo*men"tous\, a. [Cf. L. momentosus rapid,
momentary.]
Of moment or consequence; very important; weighty; as, a
momentous decision; momentous affairs. -- Mo*men"tous*ly,
adv. -- Mo*men"tous*ness, n.
[1913 Webster]
WordNet (r) 3.0 (2006):
momentous
adj 1: of very great significance; "deciding to drop the atom
bomb was a very big decision"; "a momentous event"