An Etymological Dictionary of the German Language/gediegen

by Friedrich Kluge

gediegen, adj., ‘solid, pure, concise, pithy,’ from MidHG. gedigen, adj., ‘adult, firm, hard, clear, pure,’ OHG. gidigan, adj., ‘aged, advanced in years, earnest, pure, chaste’; prop. a partic. of gidihan (g by a grammatical change is the necessary form of h in the partic.); AS. preserves the older participial form of the e-gradation, geþungen, ‘complete,’ so too OSax. thungan.