The year, month, and day of someone's birth; date of birth(noun)
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Use "birthdate" in a sentence
"Often, his birthdate is recorded as March 15, 1767 in South Carolina, but many biographers claim that he was born to his Irish parents on their journey to America."
"He's birthdate is listed as Jan. 1, 1994 in the 2005, 2006 and 2007 registration lists found by the AP."
"Extra special added surprise: if your birthdate is not set, the options to show adult content are disabled."