D defs.my
Entry 2 senses Webster, 1913

Portentous

/pôr-tĕn'-təs/ · Por·tent·ous · IPA /pɔrˈtɛn(t)əs/
01 a. Of the nature of a portent; containing portents; foreshadowing, esp. foreshadowing ill; ominous.
  1. 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. 2.
    Hence: Monstrous; prodigious; wonderful; dreadful; as, a beast of portentous size.