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 announcement, made on star Teja Sajja‘s birthday, also confirms the film’s cast and creative team. — Naman Ramachandran, Variety, 23 Aug. 2026

And so, without further ado, on Kim Cattrall’s 70th birthday, here are 70 of the greatest Samantha Jones quotes of all time. — Daisy Jones, Vogue, 22 Aug. 2026

Friday, August 21 Panettiere would have celebrated her 37th birthday on this day. — Julianna Bragg, CNN Money, 22 Aug. 2026

This was twenty-seven years ago—March, 1999, about a week before my twenty-first birthday—but to this day a whiff of Acqua di Giò brings back the nausea. — Ledio Cakaj, New Yorker, 22 Aug. 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