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

On visits later in the spring of my fourteenth birthday, Jim holds court on the small bank under the birch trees outside Stora Mans. —Literary Hub, 28 Jan. 2026

Meanwhile, Valerie Bertinelli touched on the topic of immigration in a post dedicated to her late ex-husband, Eddie Van Halen, on what would have been his 71st birthday. —Sarah Sotoodeh , Lauryn Overhultz, FOXNews.com, 27 Jan. 2026

For their birthdays, our tradition is to take them somewhere fun. —Meg Anderson, NPR, 27 Jan. 2026

The lower level would serve as an assembly and event space for weddings, baptisms, birthdays and cultural events, supported by a full kitchen and bar service during social events. —Adrienne Davis, jsonline.com, 27 Jan. 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