plural of birthday

Third-person singular simple present indicative form of birthday

Any of twelve gemstones traditionally associated with the month of one's birth. / Any of a similar list of less costly substitutes.

(cryptography) A covert method of decryption exploiting the so-called birthday paradox.

(probability theory) The mathematics problem that concerns the probability there exist two people in a random group who share a birthday.

the year, month, and day of someone's birth; date of birth

plural of birthdate

plural of birthday boy

plural of birthmark

Archaic spelling of birthday.