köken: Learned borrowing from Ancient Greek διετής (dietḗs). By surface analysis, δι- from δις ("twice") (di- from dis ("twice")) + -ετής (-etís) from έτ(ος) n (ét(os), “year”) + -ής (-ís, suffix for adjectives).
köken: Etymology tree Esperanto duono Proto-Indo-European *(H)yeh₁-der.? Proto-Indo-European *yóh₁r̥der. Proto-Germanic *jērą Proto-West Germanic *jār Old High German jār Middle High German jār German Jahrbor. ▲ Proto-West Germanic *jār Old English ġēar Middle English yeer English yearbor. ▲ Old High German jār Yiddish יאָר (yor)bor. ▲ Proto-West Germanic *jār Old Dutch jār Middle Dutch jâer Dutch…