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

Just six weeks prior, less than a month after his 17th birthday, Wilson had run 45.66 indoors to better his own under-18 ‘world best’ and high school national record. —Liam Tharme, The Athletic, 23 Mar. 2025

The Three's Company actor died on Noah's 5th birthday, during his first week of preschool. —Stephanie Sengwe, People.com, 23 Mar. 2025

Mike first sent the card to Al for his birthday in January 1936. —Graham Womack, Sacramento Bee, 23 Mar. 2025

Foreman was down on all of the scorecards when the knockout happened, and just short of his 46th birthday, Foreman had become the heavyweight champion. —Brian Mazique, Forbes, 22 Mar. 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