portentous
1 alarming, bodeful, crucial, fateful, forbidding, important, menacing, minatory, momentous, ominous, significant, sinister, threatening
2 amazing, astounding, awe-inspiring, extraordinary, miraculous, phenomenal, prodigious, remarkable, wondrous (archaic or literary)
3 bloated, elephantine, heavy, pompous, ponderous, pontifical, self-important, solemn