FORMIDABLE
formidable, redoubtable, unnerving
(adjective) inspiring fear; “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 grey wall”
formidable
(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”
Source: WordNet® 3.1
Etymology
Adjective
formidable (comparative more formidable, superlative most formidable)
Causing fear, dread, awe, or discouragement as a result of size, strength, or some other impressive feature; commanding respect; causing wonder or astonishment.
Difficult to defeat or overcome.
Source: Wiktionary
For"mi*da*ble, a. Etym: [L. formidabilis, fr. formidare to fear,
dread: cf. F. formidable.]
Definition: Exciting fear or apprehension; impressing dread; adapted to
excite fear and deter from approach, encounter, or undertaking;
alarming.
They seemed to fear the formodable sight. Dryden.
I swell my preface into a volume, and make it formidable, when you
see so many pages behind. Drydn.
Syn.
– Dreadful; fearful; terrible; frightful; shocking; horrible;
terrific; tremendous.
Source: Webster’s Unabridged Dictionary 1913 Edition