5
critical(adjective, bad, big, heavy, significant)
5
direful(adjective, fear, black, warn, luck)
5
marvelous
5
unpromising
4
awe-inspiring(adjective, fear)
4
baneful(adjective, warn, luck)
4
calamitous
4
exceptional
4
fabulous
4
fatal
4
fraught(adjective, momentous)
4
incredible
4
indescribable
4
marvellous(adjective, great, excellent, superb, super)
4
oracular(adjective, black, baleful, bodeful, prophetic)
4
pontifical
4
unfortunate
3
dismal(adjective, black, baleful, bodeful)
3
dreadful(adjective, fear)
3
eldritch(adjective, awful, fear, black, horror)
11 years ago|12k views|share |citing 
APASmart Define. (2015). portentous thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/portentous/thesaurus/synonyms
ChicagoSmart Define. 2015. "portentous thesaurus" https://smartdefine.org/portentous/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2015, portentous thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/portentous/thesaurus/synonyms>.
MLASmart Define. "portentous thesaurus" 10 April 2015. Web. 28 September 2026. <https://smartdefine.org/portentous/thesaurus/synonyms>