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 first two episodes will be released on December 12 — the day before Swift’s 36th birthday. —Lisa Respers France, CNN Money, 13 Oct. 2025

Customize it with her name and birthday or anniversary date. —Christa Joanna Lee, Glamour, 13 Oct. 2025

Approximately 50 people gathered Sunday evening to celebrate the life and upcoming birthday of Keiairra Travis after a hit-and-run killed her early Saturday morning. —Anna Kleiber, jsonline.com, 13 Oct. 2025

To mark what would have been John Lennon’s 85th birthday, Propstore is auctioning off a handful of rare artifacts with ties to the late, great Liverpudlian musician. —Rachel Cormack, Robb Report, 13 Oct. 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