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

Two of the artists who are on the bill for the upcoming birthday event shared comments in a statement. —Paul Grein, Billboard, 10 July 2025

With a bow in her hair and an arm filled with temporary tattoos, a teeny-tiny Harper snuggled up to her dad in this sweet post shared on her 10th birthday by dad. —Alexandra Schonfeld, People.com, 10 July 2025

The two often send one another loving birthday messages on Instagram–Jones wrote one for Will in May. —Elizabeth Ayoola, Essence, 10 July 2025

The new loyalty program, called Club JSX, offers 5 percent rebates for future flight credit based on purchases, plus other perks such as birthday bonuses and personalized offers. —Michael Cappetta, Travel + Leisure, 10 July 2025

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