Portentous /(?)/

Por·tent·ous

Portentous

a.
  1. Of the nature of a portent; containing portents; foreshadowing, esp. foreshadowing ill; ominous.
    For, I believe, they are portentous things.
    Victories of strange and almost portentous splendor.
  2. Hence: Monstrous; prodigious; wonderful; dreadful; as, a beast of portentous size.