fun
Americannoun
verb (used with or without object)
adjective
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Informal. of or relating to fun, especially to social fun.
a fun thing to do; really a fun person; the funnest game.
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Informal. whimsical; flamboyant.
The fashions this year are definitely on the fun side.
idioms
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for / in fun, as a joke; not seriously; playfully.
His insults were only in fun.
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make fun of, to make the object of ridicule; deride.
The youngsters made fun of their teacher.
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like fun, certainly not; of doubtful truth.
He told us that he finished the exam in an hour. Like fun he did!
noun
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a source of enjoyment, amusement, diversion, etc
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pleasure, gaiety, or merriment
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jest or sport (esp in the phrases in or for fun )
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facetious amusement; frivolous activity
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informal
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(adverb) quickly; vigorously
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(interjection) not at all! certainly not!
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to ridicule or deride
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(modifier) full of amusement, diversion, gaiety, etc
a fun sport
verb
Etymology
Origin of fun
First recorded in 1675–85; dialectal variant of obsolete fon “to befool”; see fond 1 ( def. )
Explanation
When you are having fun, you are having a good time. Watching little kids jump around inside an inflatable bouncy house, you can instantly tell how much fun they're having. There is no mistaking fun when you're having it, and it's generally used to mean exactly what it sounds like, some activity or experience that's purely enjoyable. When fun takes the form of an adjective, it's informal, not strictly grammatically correct. So while you can say, "Being with her is so much fun," you can't correctly say, "She is such a fun girl." Fun turns a little bit mean when you're making fun of, or teasing, your friend. In this case, it might be fun for you, but it's probably not very much fun for him.
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.
Fun fact: The American colonists—or tax-dodging rebels, as some in Britain still jokingly call them—got their independence from Charles’ great-great-great-great-great grandfather, George III.
From The Wall Street Journal • Apr. 27, 2026
In an ironic twist, given the song’s all-grown-up-at-18 energy, “Boyfriend” was blocked from No. 1 by “We Are Young” from Jack Antonoff’s old band, Fun.
From Los Angeles Times • Apr. 16, 2026
Fun lie: The titular characters in the 1997 comedy movie “Romy and Michele’s High School Reunion” claimed they invented the office staple to impress their former classmates.
From The Wall Street Journal • Apr. 4, 2026
There is even an arcade-style game, "Water Gun Fun" -- a reminder that at CPAC, politics is rarely presented without a layer of spectacle.
From Barron's • Mar. 28, 2026
As Mr. Fun turned away to talk to them, Adam came swaggering over to the Hardys.
From "Trouble at the Arcade (The Hardy Boys: Secret Files, #1)" by Franklin W. Dixon
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.
