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

Their sisters Kim Kardashian and Khloe Kardashian and mom Kris Jenner attended the birthday getaway, sharing their own snapshots from the trip. —Sarah Sotoodeh, FOXNews.com, 17 Nov. 2025

Surovtsev had never so much as skipped an event at the girls’ school before missing his oldest daughter’s fifth birthday later in August. —Danya Gainor, CNN Money, 17 Nov. 2025

The fact that Prince Harry and Meghan Markle attended Kris Jenner’s 70th birthday party has brought on a lot of drama. —Lizzie Lanuza, StyleCaster, 17 Nov. 2025

The pop-up anchors the house’s 130th birthday celebrations and highlights the brand’s ties to the French capital. —Rhonda Richford, Footwear News, 17 Nov. 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