From Longman Dictionary of Contemporary Englishredoubtablere‧doubt‧a‧ble /rɪˈdaʊtəbəl/ adjective literary ALFRIGHTENEDsomeone who is redoubtable is a person you respect or fear He had never met a more redoubtable fighter.
Examples from the Corpus
redoubtable• She was rechristened Nancy Blackett in honour of the redoubtable Amazon pirate who had, in a sense, paid for her.• He was a redoubtable debater with a caustic tongue in polemics and a nice touch in irony in writing.• Then a flaring swish as its propellant ignited, accelerating it helter-skelter accumulating redoubtable kinetic energy.• Smiles all round as Alton men thankfully take possession against the redoubtable ladies.• Nevertheless I had a brief affair with the redoubtable Maud.• It is sponsored by champagne house Veuve Clicquot, founded by the redoubtable Mme Clicquot.• All the same, Amstrad seems to be an unnecessarily tough test, even for the redoubtable Mr Potter.• Then came the Edrichs and the redoubtable Rought-Roughts.Origin redoubtable (1300-1400) French redouter “to fear”, from douter “to doubt” 