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

Related Articles Vivianna Blanch is now chief marketing officer at Dermalogica, which is celebrating its 40th birthday this year. — Noor Lobad, Footwear News, 29 Sep. 2026

Twelve teenagers were shot early Sunday morning after gunfire broke out at a birthday party in Macon, Georgia. — Carter Schroppe, The Washington Examiner, 28 Sep. 2026

That’s without going into reports that Meghan and Jenner didn’t get along after an infamous photo incident, when the Duke and Duchess of Sussex attended Jenner’s birthday party. — Stylecaster Editors, StyleCaster, 28 Sep. 2026

The gathering was a birthday party that had moved to the park after the group was asked to leave an Airbnb in Jones County, Bibb County Sheriff David Davis said. — CBS News, 28 Sep. 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