birth·​day | \ ˈbərth-ˌdā How to pronounce birthday (audio) \

Definition of birthday

1a : 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.
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Recent Examples on the Web

Probably because my birthday is six days before Halloween. Jessica Peralta, Daily Pilot, "Creep It Real OC Expo is for Halloween fans who want to kick their spooky festivities up a notch," 16 Sep. 2019 Jayden turned 13 on Thursday and Sean celebrated his 14th birthday on Saturday. Sonja Haller, USA TODAY, "Britney Spears posts throwback pic to celebrate sons' b-days. 'Mamma loves you'," 16 Sep. 2019 Star Saoirse Ronan earned three Oscar nominations before her 25th birthday. Los Angeles Times, "‘Jojo Rabbit’ wins Toronto film festival audience award, as Oscar season has few clear front-runners," 15 Sep. 2019 He was born on October 1, 1998 in Hartford, CT and was just a few weeks shy of celebrating his 21st birthday., "Nathan P. Sterling," 15 Sep. 2019 Owen Carey died after celebrating his 18th birthday with a meal at a Byron Burger, a chain restaurant in London, in 2017. Nicole Acevedo, NBC News, "British teen allergic to dairy died after burger joint said his birthday meal was safe," 14 Sep. 2019 The outcomes for these women’s babies are also disproportionately poor: Black and Native American babies are more likely than white babies to die by their first birthdays., "a new survey of 2,700 US women published in June," 14 Sep. 2019 So, this season, with three World Series championships in the rear-view mirror, his 33rd birthday looming and the greatest offensive struggles of his career, Posey still deserves and receives the benefit of the doubt. Ann Killion,, "Why Giants’ Buster Posey still gets benefit of doubt in frustrating year," 13 Sep. 2019 Owen Carey, who was celebrating his 18th birthday at the restaurant in 2017, told waiting staff about his allergies before ordering a fried chicken burger coated in buttermilk at a London branch of the restaurant. Wire Service, The Mercury News, "Teen died after eating burger despite telling staff about his allergy, coroner rules," 13 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'birthday.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of birthday

14th century, in the meaning defined at sense 2

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Statistics for birthday

Last Updated

15 Oct 2019

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Time Traveler for birthday

The first known use of birthday was in the 14th century

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More Definitions for birthday



English Language Learners Definition of birthday

: the day when someone was born or the anniversary of that day
: the day when something began


birth·​day | \ ˈbərth-ˌdā How to pronounce birthday (audio) \

Kids Definition of birthday

1 : the day or anniversary of someone's birth
2 : a day of beginning Our town just celebrated its 150th birthday.

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More from Merriam-Webster on birthday

Rhyming Dictionary: Words that rhyme with birthday

Spanish Central: Translation of birthday

Nglish: Translation of birthday for Spanish Speakers

Britannica English: Translation of birthday for Arabic Speakers

Comments on birthday

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to be made up of

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