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 event was put on by Freedom 250, a public-private partnership set up by the president to promote the nation's milestone birthday. — Zac Anderson, USA Today, 25 June 2026

Many also include birthday party packages, scout patch programs and family classes where adults cook alongside their kids. — Lauren Schuster, Miami Herald, 24 June 2026

Rita Zajko had reached out to her daughter on her birthday -- which fell on New Year’s Eve -- apologizing for the rift between them and seeking to mend their relationship, according to Rouse. — Nadine El-Bawab, ABC News, 24 June 2026

But instead of giving away 240 hot dogs for its 24th year of business this year, founder and managing partner Bourke Harvey decided to give away 250 free hot dogs in honor of America’s 250th birthday celebration. — Ella Gonzales, Fort Worth Star-Telegram, 24 June 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