O.E. geoguð "youth," related to geong "young," from W.Gmc. *jugunthiz, altered from P.Gmc. *juwunthiz (cf. O.S. juguth, O.Fris. jogethe, M.Du. joghet, Du. jeugd, O.H.G. jugund, Ger. Jugend, Goth. junda "youth;" see young) by influence of its contrast, *dugunthiz "ability"
(source of O.E. duguð). In M.E., the medial -g- became a yogh, which then disappeared. Youthful first attested 1561.
"They said that age was truth, and that the young Marred with wild hopes the peace of slavery" [Shelley]