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
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.
I met a mom-and-daughter celebrating the mom’s 60th birthday in Hawaii.
From The Wall Street Journal • May 8, 2026
Jane Kendrick, from the farm, said Sir David had visited them in the early 2000's to film the blue morpho's and they wanted to do something to celebrate the conservationist on his 100th birthday.
From BBC • May 8, 2026
Ahead of the country’s 250th birthday, we need to more discussion of what America is and what we want it to look like — without mincing words.
From Salon • May 8, 2026
Sir David Attenborough, who is marking his 100th birthday today, has travelled to virtually every corner of Earth as part of his quest to educate others about the natural world.
From BBC • May 8, 2026
His birthday isn’t for another few months, and that doesn’t explain why Emma’s here.
From "South of Somewhere" by Kalena Miller
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.
