fat

American  

[fat] / fæt /

adjective

fatter, fattest

1. having too much flabby tissue; corpulent; obese.

   a fat person.

   Synonyms:

   pudgy, adipose, portly

   Antonyms:

   thin

2. plump; well-fed.

   a good, fat chicken.

3. consisting of or containing fat; greasy; oily.

   fat gravy; fat meat.

   Synonyms:

   fatty, unctuous

   Antonyms:

   lean

4. profitable, as an office.

   a fat job on the city commission.

   Synonyms:

   remunerative, lucrative

5. affording good opportunities, especially for gain.

   a fat business contract.

6. wealthy; prosperous; rich.

   He grew fat on dishonest profits.

7. big, broad, or extended; thick.

   a fat sheaf of bills.

8. plentiful; abundant.

   a fat supply of food.

   Synonyms:

   copious

9. plentifully supplied.

   a fat larder; a fat feast.

10. dull; stupid.

    fat clumsiness of manner.

    Synonyms:

    sluggish

    Antonyms:

    clever

11. abounding in a particular element.

    Fat pine is rich in resin.

12. (of paint) having more oil than pigment.

13. (of coal) highly bituminous; rich in volatile hydrocarbons.

14. Ceramics. long.

15. fertile, as land.

    Everything grows in this fat soil.

    Synonyms:

    productive, fruitful, rich

    Antonyms:

    barren, sterile

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noun

1. any of several white or yellowish greasy substances, forming the chief part of adipose tissue of animals and also occurring in plants, that when pure are colorless, odorless, and tasteless and are either solid or liquid esters of glycerol with fatty acids; fats are insoluble in water or cold alcohol but soluble in ether, chloroform, or benzene: used in the manufacture of soap, paints, and other protective coatings and in cooking.

2. animal tissue containing much of this substance; loose flesh; flabbiness.

   to have rolls of fat around one's waist.

3. the richest or best part of anything.

4. obesity; corpulence.

   In his later years, he inclined to fat.

5. Slang. especially profitable or advantageous work.

6. an overabundance or excess; superfluity.

7. action or lines in a dramatic part that permit an actor to display abilities.

8. Also called lift.  Typesetting. Also matter that can be composed easily and profitably, especially from standing type, illustrations, or the like.

   fat work.

verb (used with or without object)

fatted, fatting

1. to make or become fat.

idioms

1. chew the fat. chew.

2. the fat of the land, the best or richest of anything obtainable.

   to live on the fat of the land.

3. a fat chance, a very slight chance; small probability.

   A fat chance he has of winning the title!

4. the fat is in the fire,

   1. an irrevocable action or chain of events has been started; the die is cast.

      Now that they have been given an ultimatum, the fat is in the fire.

   2. the decision, whether good or bad, has been made.

   3. the crisis is imminent.

5. a fat lot, little or not at all.

   A fat lot they care about anyone else's troubles!

fat British  

/ fæt /

noun

1. any of a class of naturally occurring soft greasy solids that are esters of glycerol and certain fatty acids. They are present in some plants and in the adipose tissue of animals, forming a reserve energy source, and are used in making soap and paint and in the food industry See also oil

2. vegetable or animal tissue containing fat

3. corpulence, obesity, or plumpness

4. the best or richest part of something

5. a part in a play that gives an actor a good opportunity to show his talents

6. slang

   1. to argue over a point

   2. to talk idly; gossip

7. an irrevocable action has been taken, esp one from which dire consequences are expected

8. the best that is obtainable

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adjective

1. having much or too much flesh or fat

2. consisting of or containing fat; greasy

   fat pork

3. profitable; lucrative

   a fat year

4. affording great opportunities

   a fat part in the play

5. fertile or productive

   a fat land

6. thick, broad, or extended

   a fat log of wood

7. having a high content of a particular material or ingredient, such as resin in wood or oil in paint

8. plentifully supplied

   a fat larder

9. slang empty; stupid

   get this into your fat head

10. slang very little or none; minimal (in phrases such as a fat chance , a fat lot of good , etc)

verb

1. to make or become fat; fatten

fat Scientific  

/ făt /

1. Any of a large number of oily compounds that are widely found in plant and animal tissues and serve mainly as a reserve source of energy. In mammals, fat, or adipose tissue, is deposited beneath the skin and around the internal organs, where it also protects and insulates against heat loss. Fat is a necessary, efficient source of energy. An ounce of fat contains more than twice as much stored energy as does an ounce of protein or carbohydrates and is digested more slowly, resulting in the sensation of satiety after eating. It also enhances the taste, aroma, and texture of food. Fats are made chiefly of triglycerides, each molecule of which contains three fatty acids. Dietary fat supplies humans with essential fatty acids, such as linoleic acid and linolenic acid. Fat also regulates cholesterol metabolism and is a precursor of prostaglandins.

2. See more at saturated fat unsaturated fat

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fat More Idioms  

More idioms and phrases containing fat

• chew the fat
• kill the fatted calf

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Usage

What is a basic definition of fat? Fat is commonly used as a way to describe someone as obese or overweight. This is most often used in a critical, judgmental, or mean way. In contrast, words like obese and overweight are more often used in a neutral way, such as in a medical context in the discussion of a person’s health (though they too can be used in a judgmental or mean way). This sense of fat isn’t always used in a negative way. Some people might call others or themselves fat in a way that’s not intended to be critical, as in I’m fat and I’m fabulous and all the body-shamers will just have to deal with it. Sometimes, people replace the word fat with words intended to be more polite or euphemistic, such as heavy, heavyset, plump, and chubby. However, these words still focus on a person’s weight or appearance in a way that can be demeaning or objectifying. As a noun, fat refers to the greasy substance that forms some types of tissue in the body of humans and animals (some of which the body stores and uses for energy) and some plants. The word is often used more casually to refer to a person’s excess flesh, as in belly fat.  In the context of nutrition, fat refers to this kind of substance in the foods we eat. Foods from animals, such as meat, milk, and eggs, all contain fat. But so do some plant-based foods, such as nuts, avocados, and olive oil. However, there are different kinds of fat, such as saturated fat, unsaturated fat, and trans-fat, each of which can have different effects on a person’s nutrition and health. In general, it’s usually recommended not to consume too much fat. However, some fats are necessary in a diet because they help the body to absorb vitamins. The nutrition label on food products usually tell you exactly how much fat and what kinds of fats are in them. The word fat is common and has many other meanings as an adjective, a noun, and even a verb. Example: This diet is based on avoiding foods that are high in fat.  

Related Words

See stout.

Other Word Forms

• defat verb (used with object)
• fatless adjective
• fatlike adjective
• fatly adverb
• fatness noun
• fattish adjective
• overfat adjective
• unfatted adjective

Etymology

Origin of fat

First recorded before 1000; Middle English; Old English fǣtt, originally the past participle of fǣtan “to cram, load, adorn”; cognate with Gothic fētjan “to adorn”; akin to vat

Explanation

Fat is a form of body tissue on animals. It’s a squishy layer that stores energy and protects organs. Fat is also an adjective meaning chubby or thick, as in a fat piglet or a fat wallet full of money. Some foods, like butter or avocado, have fat. Deep fried chocolate bars have a lot of fat. Humans, and other animals, need to consume some fat to maintain optimal health and absorb certain vitamins. The word fat can be applied not just to people, animals, or deep-fried food, but to any inanimate object that is notably big. Your brother likes reading comics, while you prefer fat books like War and Peace and The Complete Works of Shakespeare.

Example Sentences

This is what made me what I am today — fat and unemployed.

From Los Angeles Times • Apr. 11, 2026

"The second one shows global mild stranding of the mesenteric fat - that meant widespread abdominal inflammation".

From BBC • Apr. 8, 2026

Videos he’s posted show them howling with laughter while dozens of fat fish jump all around them.

From The Wall Street Journal • Apr. 8, 2026

Dry spices scattered into cream taste dusty; spices warmed in fat become aromatic, expansive.

From Salon • Apr. 7, 2026

But Nim got another load and then another, till she had twenty fat coconuts heaped on the rocks, and then she hurled them into the water one by one.

From "Nim’s Island" by Wendy Orr

Related Words

• big
• bulging
• bulky
• chunky
• heavy
• hefty
• inflated
• large
• meaty
• obese
• plump
• well-fed