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 feeling is mutual; October 24, his birthday, was named Jaylen Brown Day by the city. — Rembert Browne, Architectural Digest, 2 Nov. 2026

Pagani has just unveiled the Huayra 70 Anima, a final 70th birthday tribute to its founder, Horacio Pagani. — Bryan Hood, Robb Report, 2 Nov. 2026

Bushby had a thirst for adventure, but his mission only came into focus when his father, Keith, sent him a birthday card in the mid-90s. — ABC News, 2 Nov. 2026

Beech is best for anyone traveling with children, while for larger groups, renting all three would be a fun way to celebrate a birthday. — Chloe Laws, Condé Nast Traveler, 2 Nov. 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