"redoubtable" in the adjective sense
1. formidable, 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 grey wall"
worthy of respect or honor
"born of a redoubtable family"
Source: WordNet® (An amazing lexical database of English)
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