birthday

noun

birth·​day ˈbərth-ˌdā 

1

a

: the day of a person's birth

b

: a day of origin

2

: an anniversary of a birth

her 21st birthday

Examples of birthday in a Sentence

Her birthday is September 30th.

Today is his 21st birthday.

The company just celebrated its 50th birthday.

Recent Examples on the Web

Yamal made his first-team debut in April 2023, two and a half months before his 16th birthday. — Jack Lang, New York Times, 18 July 2026

One last July birthday shout-out, to our youngest grandson, Teddy. — Mike Lupica, New York Daily News, 18 July 2026

Neither method requires you to share your name, birthday, or any form of ID. — Ravi Iyer, Time, 18 July 2026

Kidman, who recently celebrated her 59th birthday, ensured Antonia’s 55th birthday celebration was one for the books with a luxurious stop in Portofino. — Lara Walsh, InStyle, 18 July 2026

Word History

First Known Use

14th century, in the meaning defined at sense 2

Phrases Containing birthday

• birthday suit

Rhymes for birthday

• airway
• allay
• archway
• array
• ashtray
• assez
• astray
• aue
• away
• ballet
• belay
• beltway

Kids Definition

birthday

noun

birth·​day ˈbərth-ˌdā 

1

: the day or anniversary of one's birth

2

: the day or anniversary of a beginning