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

Donna, the on-site restaurant, is the city’s quintessential special occasion spot for everything from birthday parties to date nights. —Condé Nast, Condé Nast Traveler, 25 Mar. 2026

Releasing an old video, which conveniently omits context, on their son’s birthday is a reprehensible attempt to distract from his own behavior. —Jack Dunn, Variety, 24 Mar. 2026

Irving celebrated his 34th birthday, while Kidd turned 53. —Mike Curtis, Dallas Morning News, 24 Mar. 2026

Two-thirds of children who were held back had summer birthdays between June and August — near the kindergarten enrollment cutoff dates in most states — and would have been young for their grade. —Kate Sequeira, Los Angeles Times, 24 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