diet

¹ American  

[dahy-it] / ˈdaɪ ɪt /

noun

1. food and drink considered in terms of its qualities, composition, and its effects on health.

   The ad shows milk and dairy as a wholesome part of our daily diet.

2. a particular selection of food, especially as designed or prescribed to improve a person's physical condition or to prevent or treat a disease.

   A diet low in sugar is often recommended for diabetes prevention.

3. a selection of food that emphasizes caloric restriction or otherwise limits the amount a person eats, usually intended to induce weight loss.

   No pie for me, I'm on a diet.

4. the foods eaten, as by a particular person or group.

   The Mediterranean diet consists historically of fish, fruit, vegetables, whole grains, and nuts.

5. food or feed habitually eaten or provided.

   The rabbits were fed a diet of carrots and lettuce.

6. anything that is habitually provided or partaken of.

   Television has given us a steady diet of reality shows and police procedurals.

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adjective

1. suitable for consumption as part of a selection of food intended to induce weight loss.

   I usually drink diet soft drinks.

2. formulated to be lower in calories, fat, sugar, etc. than a similar food.

   The diet version of the cookie does taste different.

verb (used without object)

dieted, dieting

1. to select or limit the food one eats to improve one's physical condition or to lose weight.

   I've dieted all month and lost only one pound.

2. to eat or feed according to the requirements of a particular or prescribed selection of food.

verb (used with object)

dieted, dieting

1. to regulate the food of, especially in order to improve the physical condition.

   They dieted the dog to a healthy weight of 20 pounds.

2. to feed.

diet ² American  

[dahy-it] / ˈdaɪ ɪt /

noun

1. the legislative body of certain countries, as Japan.

2. the general assembly of the estates of the former Holy Roman Empire.

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diet ¹ British  

/ ˈdaɪət /

noun

1. 1. a specific allowance or selection of food, esp prescribed to control weight or in disorders in which certain foods are contraindicated

      a salt-free diet

      a 900-calorie diet

   2. ( as modifier )

      a diet bread

2. the food and drink that a person or animal regularly consumes

   a diet of nuts and water

3. regular activities or occupations

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verb

1. (usually intr) to follow or cause to follow a dietary regimen

diet ² British  

/ ˈdaɪət /

noun

1. (sometimes capital) a legislative assembly in various countries, such as Japan

2. Also called: Reichstag.  (sometimes capital) the assembly of the estates of the Holy Roman Empire

3. Scots law

   1. the date fixed by a court for hearing a case

   2. a single session of a court

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Other Word Forms

• dieter noun
• nondieter noun
• nondieting adjective

Etymology

Origin of diet¹

First recorded in 1175–1225; Middle English noun diete “day’s journey, appointed day, way of living,” from Anglo-French, Old French diete, from Latin diaeta, from Greek díaita “way of living, diet,” equivalent to dia- dia- + -aita (akin to aîsa “share, lot”; the verb is derivative of the noun

Origin of diet²

First recorded in 1400–50; late Middle English, from Medieval Latin diēta “public assembly,” the same word as Latin diaeta with sense affected by Latin diēs “day”; diet ¹

Explanation

Diet means the usual food and drink consumed by a person or animal. A healthy diet for your pet is not the same as your diet, so you shouldn't feed your dog all your table scraps. If you limit the number of calories you eat in order to lose weight, or restrict certain foods for your health, you can also call this a diet. If you want to lose 10 pounds by summer, you might have to go on a diet. In certain countries, the word diet, though pronounced the same, has a non-food related meaning: the diet is the legislative branch of the government in countries like Japan.

Example Sentences

No longer able to afford the staple of their diet, the Egyptian people revolted.

From Barron's • Apr. 10, 2026

OK, here’s a confession: I eat a vegan diet.

From Los Angeles Times • Apr. 10, 2026

Scientists have explored a range of possible factors, including genetics, environmental exposures, brain injuries, and diet.

From Science Daily • Apr. 9, 2026

Rhona acknowledges the environmental impact of the trend, but says she takes steps like eating a pescetarian diet and using a green energy tariff to offset the impact.

From BBC • Apr. 8, 2026

And many men also suffered from trench mouth, a severe bacterial infection of the gums, another hazard of life in the trenches, caused by poor diet, poor hygiene, and smoking.

From "The War to End All Wars: World War I" by Russell Freedman