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.
momentous adj : of very great significance; "deciding to drop the atom bomb was a very big decision"; "a momentous event" [syn: {big}]