1. [ adjective ] extremely impressive in strength or excellence

"a formidable opponent" "the challenge was formidable" "had a formidable array of compositions to his credit" "the formidable army of brains at the Prime Minister's disposal"

Related terms: impressive
2. [ adjective ] inspiring fear
Synonyms: redoubtable unnerving

"the formidable prospect of major surgery" "a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"- G.H.Johnston "something unnerving and prisonlike about high gray wall"

Related terms: alarming
Similar spelling:   formidably