birthday

American  

[burth-dey] / ˈbɜrθˌdeɪ /

noun

birthdays plural

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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Other Word Forms

Noun Inflected Forms

• birthdays
  plural

Etymology

Origin of birthday

Middle English word dating back to 1350–1400; see origin at 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

At one point in the evening, the crowd sang happy birthday to the president.

From BBC • Jun. 25, 2026

For example, if your birthday is in July, the rule would apply only from January through June of that year.

From MarketWatch • Jun. 24, 2026

Now the World Cup's record goalscorer and, as he celebrates his 39th birthday, still seemingly untouchable.

From BBC • Jun. 24, 2026

“On my birthday, my wish list was always from Bed Bath & Beyond,” she said.

From The Wall Street Journal • Jun. 22, 2026

I tried not to think about my destiny too much, but on my birthday I always did.

From "Rump: The (Fairly) True Story of Rumpelstilskin" by Liesl Shurtliff