Por·tent·ous a.
1. Of the nature of a portent; containing portents; foreshadowing, esp. foreshadowing ill; ominous.
For, I believe, they are portentous things. --Shak.
Victories of strange and almost portentous splendor. --Macaulay.
2. Hence: Monstrous; prodigious; wonderful; dreadful; as, a beast of portentous size.
-- Por*tent*ous*ly, adv. -- Por*tent*ous*ness, n.
◄ ►