O.E. dohtig "competent, good, valiant," from dyhtig "strong," related to dugan "to be fit, be able, be strong," and influenced by its p.p., dohte. All from P.Gmc. *duhtiz- (cf. M.H.G. tühtec, Ger. tüchtig, M.Du. duchtich), from PIE *dheugh- "to be fit, be of use, proper" (cf. Ger. Tugend "virtue," Gk. teukhein "to make ready," Ir. dual "becoming, fit," Rus. duzij "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.