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

Hugh Jackman sang for his fellow Australian Rupert Murdoch at his 95th birthday party on Saturday. —Jack Dunn, Variety, 10 Mar. 2026

That call requesting her to come in for an interview came on her birthday in January. —Elizabeth Marie Himchak, San Diego Union-Tribune, 10 Mar. 2026

Five Guys is offering another burger promotion for its 40th birthday. —Taylor Ardrey, USA Today, 10 Mar. 2026

The lawmakers also reference the particular focus on this year’s parade, where the route has been reversed to mark America’s 250th birthday and coincide with the historic route that was used during the British evacuation of Boston. —Gayla Cawley, Boston Herald, 10 Mar. 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
• 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