Emily Dickinson Lexicon

portentous, adj. [L. portentōsus < portentum, sign, omen, monster, marvelous tale.] (webplay: ignorance).

1. Foreboding; prophetic; [fig.] secretive; implied; implicit; unspoken.
2. Inevitable; impending; imminent; destined; pre-determined.
3. Enormous; immense; monstrous; awful.
4. Strange; unusual; peculiar; queer; curious; remarkable; extraordinary; amazing; shocking; appalling; dismaying; disconcerting.