The story
- Proto-Germanic · inherited from*jēradagaz
- Proto-West Germanic · inherited from*jāradag“day of the year, yearly day”
- Old English · inherited from*ġēardæġ
- Middle English · inherited fromȝereday
- English todayyearday
From Middle English ȝereday, ȝerdai (“anniversary”), from Old English *ġēardæġ (compare Old English ġeārdagas (“days of yore”)), from Proto-West Germanic *jāradag (“day of the year, yearly day”), from Proto-Germanic *jēradagaz, equivalent to year + day. Cognate with West Frisian jierdei (“birthday”), Dutch jaardag (“anniversary, birthday”), German Jahrtag (“anniversary”).
Etymology from Wiktionary, CC BY-SA 4.0.