formidable

英 ['fɔːmɪdəb(ə)l; fɔː'mɪd-] 美['fɔrmɪdəbl]

1. 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"

2. 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 gray wall"