formidable, redoubtable, unnerving -- (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")
redoubtable -- (worthy of respect or honor; "born of a redoubtable family")
(Sound)
