35
largest(adjective, feature, characteristic, size)
35
mountain(adjective, feature, characteristic, size)
35
swingeing(adjective, feature, characteristic, size)
34
powerful(adjective, strong, tough, difficult, overwhelming)
31
scary(adjective, feeling, cause, fear, frightening)
26
fearful(adjective, great, awful, fear, horrible)
22
intimidating(adjective, difficult, awful, horrible, shocking)
20
awesome(adjective, great, tough, difficult, wonderful)
18
frightful(adjective, great, tough, terrible, fear)
13
onerous(adjective, tough, severe, difficulty, difficult)
13
terrible(adjective, appearance, bad, great, nasty)
13
arduous(adjective, tough, severe, difficulty, rough)
12
dreadful(adjective, great, unpleasant, awful, terrible)
12
redoubtable(adjective, tough, awful, terrible, fear)
12
tough(adjective, strong, severe, difficulty, rough)
12
impressive(adjective, tough, difficult, awful, wonderful)
12
appalling(adjective, bad, great, tough, fear)
12
laborious(adjective, tough, severe, difficulty, rough)
11
difficult(adjective, hard, tough, severe, evil)
11
dire(adjective, tough, awful, fear, horrible)
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APASmart Define. (2015). formidable thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/formidable/thesaurus/synonyms
ChicagoSmart Define. 2015. "formidable thesaurus" https://smartdefine.org/formidable/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, formidable thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/formidable/thesaurus/synonyms>.
MLASmart Define. "formidable thesaurus" 17 July 2015. Web. 21 September 2026. <https://smartdefine.org/formidable/thesaurus/synonyms>