Por*tent"ous (?), a. [L. portentosus.]
1.
Of the nature of a portent; containing portents; foreschadowing, esp. foreschadowing 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.
Roscommon.
-- Por*tent"ous*ly, adv. -- Por*tent"ous*ness, n.
© Webster 1913.