Synonyms of portentous

2 Syllables
doomed, solemn, fated, parlous, haunting, thrilling, doomful, pompous, delphian, fustian, grabber, loury
3 Syllables
important, alarming, augural, jeopardous, amazing, ominous, lowery, astounding, blackhearted, destined, fateful, ill-boding, impendent, dangerous, hellfire, impending, prophetic, ill-fated, puffed-up, inspiring, sinister, threatening, intriguing
4 Syllables
malificent, inauspicious, phenomenal, dangersome, suggestive, oracular, minatory, precursive, remarkable
5 Syllables
apocalyptic, revelational, exhilarating, comminatory, extraordinary, fire-and-brimstone, premonitory
6 Syllables
apocalyptical