-au̇d.əbəl, -au̇təb- adjective
Etymology: Middle English redoutable, from Middle French, from redouter + -able
1.
a. : causing fear or alarm : formidable
a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic — G.H.Johnston
redoubtable gains made by the Communist Party — Max Ascoli
b. : inspiring awe or reverence : august , eminent
that redoubtable scholar of Spain's golden age — Carol Bache
2. : doughty , illustrious
a nimble-witted … guest, as redoubtable with a clue as he is at a press conference — New York Herald Tribune
born … of the redoubtable flour-milling family — New Yorker