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
The Riverside Drive and Ponca Avenue event, hosted by Los Angeles City Councilman Adrin Nazarian, celebrated Phil Roman's 95th birthday and the joy his career achievements bring to so many.
—
Julie Sharp, CBS News, 22 Dec. 2025
Ripples in a Celestial Pond The iconic Hubble Space Telescope celebrated its 35th birthday this year, and the beloved observatory is still going strong.
—Meghan Bartels, Scientific American, 22 Dec. 2025
In her comments, many were confused as to why OP would think she'd be celebrated on her son's birthday.
—Hannah Sacks, PEOPLE, 22 Dec. 2025
Lauren Sánchez Bezos and Jeff Bezos rolled through Aspen this week on their trusty steed—sorry, private jet—to celebrate Sánchez Bezos’s 56th birthday.
—Vogue, 22 Dec. 2025
See All Example Sentences for birthday
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Julie Sharp, CBS News, 22 Dec. 2025
Ripples in a Celestial Pond The iconic Hubble Space Telescope celebrated its 35th birthday this year, and the beloved observatory is still going strong.
—Meghan Bartels, Scientific American, 22 Dec. 2025
In her comments, many were confused as to why OP would think she'd be celebrated on her son's birthday.
—Hannah Sacks, PEOPLE, 22 Dec. 2025
Lauren Sánchez Bezos and Jeff Bezos rolled through Aspen this week on their trusty steed—sorry, private jet—to celebrate Sánchez Bezos’s 56th birthday.
—Vogue, 22 Dec. 2025
See All Example Sentences for birthday
Cite this Entry
“Birthday.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/birthday. Accessed 28 Dec. 2025.
Copy CitationKids Definition
birthday
noun
birth·day
ˈbərth-ˌdā
1
: the day or anniversary of one's birth
2
: the day or anniversary of a beginning
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