Origin: Latin suffix -ous
Portentous has 4 different meanings across 1 category:
of momentous or ominous significance
"such a portentous...monster raised all my curiosity"
"a prodigious vision"
ominously prophetic
puffed up with vanity
"a grandiloquent and boastful manner"
"overblown oratory"
"a pompous speech"
"pseudo-scientific gobbledygook and pontifical hooey"
Of momentous or ominous significance.