birthday

American  

[burth-dey] / ˈbɜrθˌdeɪ /

noun

1. the anniversary of a birth.

2. the day of a person's birth.

3. a day marking or commemorating the origin, founding, or beginning of something.

4. the festivities or celebration marking such a day or anniversary.

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birthday British  

/ ˈbɜːθˌdeɪ /

noun

1. 1. an anniversary of the day of one's birth

   2. ( as modifier )

      birthday present

2. the day on which a person was born

3. any anniversary

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Etymology

Origin of birthday

Middle English word dating back to 1350–1400; birth, day

Explanation

Your birthday is the day of your birth! It’s the yearly anniversary that marks the day you were born. Not everyone celebrates, but a birthday is a good excuse for a party and cake. You can use birthday both to refer to the specific day of a baby's birth, and the annual marking of that day throughout the years that follow. Sometimes people talk about the birthday of a country, group, or even a building: "It's the art museum's fiftieth birthday next year." The Old English byrddæg originally referred to the celebration of a king or saint's birth, but over the years it was extended to include everyone.

Example Sentences

The U.S. is celebrating its 250th birthday this year, but baseball has been embedded in the fabric of the country for far longer than that.

From The Wall Street Journal • Apr. 16, 2026

Cox hopes to mark his 80th birthday in June with a party in the UK, but fears his US commitments might make that tricky.

From BBC • Apr. 16, 2026

At the stadium of the Argentina soccer team he coached, Maradona was greeted with fireworks, cake and a banner wishing him a happy birthday.

From The Wall Street Journal • Apr. 16, 2026

Prosecutors allege that Pildes spent $365,000 to renovate a lakefront property in New Jersey, $124,000 on a luxury Manhattan apartment, and nearly $3,000 on a birthday dinner at a Michelin-starred restaurant in Manhattan.

From BBC • Apr. 15, 2026

I was disappointed to miss our traditional family birthday dinner because Mom always picked restaurants that served sophisticated dishes like pomegranate cheesecake and whipped truffle potatoes.

From "South of Somewhere" by Kalena Miller