flatten
Americanverb
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(sometimes foll by out) to make or become flat or flatter
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informal (tr)
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to knock down or injure; prostrate
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to crush or subdue
failure will flatten his self-esteem
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Usual US word: flat. (tr) music to lower the pitch of (a note) by one chromatic semitone
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to manoeuvre an aircraft into horizontal flight, esp after a dive
Other Word Forms
- flattener noun
- overflatten verb (used with object)
- unflattened adjective
Etymology
Origin of flatten
Explanation
When you flatten something, you crush it or level it out. If the recycling bin is getting full, you should probably flatten all those cans you're adding to it. You might flatten the batter in a cake pan before baking it, or flatten the grass along a path through a field. If your curly hair tends to get frizzy in humid weather, you may try to flatten it before you leave for school in the morning. You also might flatten yourself against a wall if you're hiding from your friend, or describe a terrible storm this way: "The tornado managed to flatten several buildings."
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.
Moderate relief is in sight this weekend, however, when forecasters predict the powerful high pressure system will start to flatten out, bringing a gradual drop in temperatures.
From Los Angeles Times • Mar. 19, 2026
“We’re just seeing this trend flatten out,” Berner said.
From MarketWatch • Mar. 12, 2026
The larger the organization, the tougher it is to flatten, keeping it slow, rigid and blind.
From The Wall Street Journal • Mar. 1, 2026
But that doesn’t necessarily flatten one more than the other.
From Salon • Feb. 26, 2026
My mother said she used a laundry iron to flatten it out before pasting it next to hers in the scrapbook.
From "Flush" by Carl Hiaasen
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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.