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

My dad’s 60th birthday was coming up, and as an avid whisky drinker with a particularly sharp nose, his dream trip has always been to explore the coastline of Islay, a Scottish island famed worldwide for its smoky, peated single malt whiskies. — Hayley Domin, Condé Nast Traveler, 14 Sep. 2026

Stickers celebrating bygone 21st birthdays cover the walls outside the bathrooms. — Dana O’Neil, CNN Money, 14 Sep. 2026

On his 71st birthday, Pope Leo XIV gave Vatican workers a raise, repealing pandemic-era salary cuts and frozen pay hikes first imposed under Pope Francis to shore up finances. — Nicole Winfield, Los Angeles Times, 14 Sep. 2026

To celebrate the Las Vegas casino operator’s 50th birthday, Station Casinos last Wednesday surprised nearly 10,000 full- and part-time employees with a stock award worth more than $70 million. — Catherina Gioino, Fortune, 14 Sep. 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