noun
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an anniversary of the day of one's birth
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( as modifier )
birthday present
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the day on which a person was born
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any anniversary
Other Word Forms
Noun Inflected Forms
Etymology
Origin of birthday
Middle English word dating back to 1350–1400; see origin at birth, day
Explanation
Your birthday is the day of your birth! It’s the yearly anniversary that marks the day you were born. Not everyone celebrates, but a birthday is a good excuse for a party and cake. You can use birthday both to refer to the specific day of a baby's birth, and the annual marking of that day throughout the years that follow. Sometimes people talk about the birthday of a country, group, or even a building: "It's the art museum's fiftieth birthday next year." The Old English byrddæg originally referred to the celebration of a king or saint's birth, but over the years it was extended to include everyone.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
A range of events have been planned to celebrate America's 250th birthday, including the rally on Wednesday tied to "The Great American State Fair" on the National Mall in Washington DC.
From BBC • Jun. 25, 2026
For example, if your birthday is in July, the rule would apply only from January through June of that year.
From MarketWatch • Jun. 24, 2026
Although Lionel Messi - who celebrates his 39th birthday today - and Cristiano Ronaldo - aged 41 - show no sign of letting up on the biggest stage.
From BBC • Jun. 24, 2026
Still, there are grounds for hope as America’s 250th birthday approaches.
From The Wall Street Journal • Jun. 23, 2026
As luck would have it, Mrs. Contreras found a family for him a few days after his tenth birthday.
From "The Way to Rio Luna" by Zoraida Cordova
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
