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

Now a grandmother, Anduha's family continues to go to Aiea Bowl for birthday parties or church gatherings. —Kathleen Wong, USA Today, 3 Nov. 2025

Hollywood star Jennifer Aniston has confirmed her relationship with new boyfriend Jim Curtis, posting a photo of him on Instagram to celebrate his birthday on Sunday. —Issy Ronald, CNN Money, 3 Nov. 2025

The couple have been dating since July and the birthday post marked a rare instance of Aniston sharing a photo of them together publicly, People reported. —Jenna Prestininzi, Freep.com, 3 Nov. 2025

Just days before, Díaz-Canel had sent Gil a congratulatory message on social media on his birthday. —Nora Gámez Torres, Miami Herald, 3 Nov. 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