fatten

American  

[fat-n] / ˈfæt n /

verb (used with object)

1. to make fat.

2. to feed (animals) abundantly before slaughter.

3. to enrich.

   to fatten the soil; to fatten one's pocketbook.

4. Cards.

   1. Poker. to increase the number of chips in (a pot).

   2. 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)

1. to grow fat.

fatten British  

/ ˈfætən /

verb

1. to grow or cause to grow fat or fatter

2. (tr) to cause (an animal or fowl) to become fat by feeding it

3. (tr) to make fuller or richer

4. (tr) to enrich (soil) by adding fertilizing agents

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Other Word Forms

• fattenable adjective
• fattener noun
• fattening adjective
• overfatten verb (used with object)

Etymology

Origin of fatten

First recorded in 1545–55; fat + -en ¹

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

They are sold to feedlots that fatten them up before being shipped to slaughterhouses.

From The Wall Street Journal • Apr. 20, 2026

It’s also possible that retailers, figuring that consumers would expect to pay more for tariffed washing machines and would assume the same effect held for dryers, charged more for the latter to fatten their profits.

From Los Angeles Times • Feb. 24, 2026

He was a skinny teenager told to go to buy milkshakes to "fatten him up".

From BBC • Nov. 7, 2025

The Katmai brown bears are famous for standing at Brooks Falls, catching sockeye salmon in their mouths to fatten up for the winter.

From Seattle Times • Sep. 29, 2023

Evidently some wild wag of an oculist set them there to fatten his practice in the borough of Queens, and then sank down himself into eternal blindness or forgot them and moved away.

From " The Great Gatsby" by F. Scott Fitzgerald

Related Words

• augment
• broaden
• build up
• swell