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

The actress celebrated her 69th birthday on Thursday, Aug. 14, by sharing an Instagram photo of herself next to a reflective message about her special day. —Ingrid Vasquez, People.com, 15 Aug. 2025

My family spends the majority of our time in the living room, whether playing and watching movies, celebrating birthdays with other family members, or even taking Sunday afternoon naps on the couch. —Katrina Cossey, Parents, 15 Aug. 2025

Dollywood is celebrating an important birthday this year. —Brandee Gruener, Southern Living, 15 Aug. 2025

The Social Security Administration (SSA) has marked the program's 90th birthday by touting its achievements under the Trump administration. —Aliss Higham, MSNBC Newsweek, 15 Aug. 2025

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
• astray
• aue
• away
• ballet
• belay
• beltway
• beret

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