deathday

The story

1. Old English · inherited fromdēaþdæġ“day of one's death, deathday”
2. Middle English · inherited fromdeth-day
3. English todaydeathday

From Middle English deth-day, deth day, dethe-day, deþ day, from Old English dēaþdæġ (“day of one's death, deathday”), equivalent to death + day. Compare birthday. Compare also German Low German Doodsdag (“deathday”), German Todestag (“deathday”), Danish dødsdag (“deathday”), Swedish dödsdag (“deathday”).