If you describe someone as redoubtable, you respect them because they have a very strong character, even though you are slightly afraid of them. He is a redoubtable fighter. = formidable. someone who is redoubtable is a person you respect or fear (redouter , from douter )
Formidable; dread; terrible to foes; as, a redoubtable hero; hence, valiant; often in contempt or burlesque
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"
having or worthy of pride; "redoubtable scholar of the Renaissance"; "born of a redoubtable family"