doughty (adj.) Look up doughty at Dictionary.com
Old English dohtig "competent, good, valiant," from dyhtig "strong," related to dugan "to be fit, be able, be strong," and influenced by its past participle, dohte.

All from Proto-Germanic *duhtiz- (source also of Middle High German tühtec, German tüchtig, Middle Dutch duchtich), from PIE *dheugh- "to be fit, be of use, proper" (source also of German Tugend "virtue," Greek teukhein "to make ready," Irish dual "becoming, fit," Russian dužij "strong, robust"). Rare after 17c.; in deliberately archaic or mock-heroic use since c. 1800. If it had survived, its modern form would be dighty.