Meaning

noun an anniversary of the day on which a person was born (or the celebration of it)

noun the date on which a person was born

originFrom Middle English birthdai, birtheday, from Old English ġebyrddæġ (“birthday”), influenced by Old Norse burðr, equivalent to birth + day. Compare Saterland Frisian Gebuursdai (“birthday”), Dutch geboortedag (“birthday”), Low German Geboortsdag (“birthday”), German Geburtstag (“birthday”), Norwegian bursdag, gebursdag (“birthday”). Eclipsed non-native Middle English nativitee (“birth, nativity,…

Etymology from Wiktionary, CC BY-SA 3.0