fatten
Americanverb (used with object)
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to make fat.
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to feed (animals) abundantly before slaughter.
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to enrich.
to fatten the soil; to fatten one's pocketbook.
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Cards.
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Poker. to increase the number of chips in (a pot).
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Pinochle. to play a card that scores high on (a trick) expected to be taken by a partner.
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verb (used without object)
verb
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to grow or cause to grow fat or fatter
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(tr) to cause (an animal or fowl) to become fat by feeding it
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(tr) to make fuller or richer
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(tr) to enrich (soil) by adding fertilizing agents
Other Word Forms
Etymology
Origin of fatten
Explanation
To fatten someone is to feed them until they become bigger and fatter. Your grandmother might see a tiny baby and say, "His mother needs to fatten him up!" A farmer might spend weeks trying to fatten his prize pigs before he sells them for meat, and you may visit relatives who keep cooking you delicious food in an attempt to fatten you up. Figuratively, you can also fatten things like your bank account, by making it larger. Before the 1550s, the verb form of this word was fat — and both fat and fatten come from the Old English word fætt, "fat or plump."
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.
Feeders are ranchers who own feedlots where they fatten cattle and sell them to meatpackers.
From The Wall Street Journal • Dec. 24, 2025
James Canton spent two years sitting beneath an 800-year-old oak tree near his home in Essex, watching acorns fatten and butterflies land on the massive knurled grey trunk.
From BBC • Jul. 14, 2025
Mountain goats deal with heavy snow, and have a short window of time to fatten up before the thick of winter.
From Seattle Times • May 22, 2024
They’re both hatched upstream and, as kids, fight their way past bullies down to the ocean, where they fatten up on marine nutrients not available in freshwater.
From Los Angeles Times • Apr. 29, 2024
“He needs to fatten up to fill out his tracksuit,” I say.
From "Without Refuge" by Jane Mitchell
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.
