diet

Etymology 1

From Middle English diet, dyet, diete, from Old French diete, from Medieval Latin dieta (“regimen, regulation; assembly”), from Latin diaeta, from Ancient Greek δίαιτα (díaita).

noun

1. The food and beverage a person or animal consumes.
   The diet of the giant panda consists mainly of bamboo.
   It is common policy to order no more diet than will be used within one month. 2013, Martin D Buckland, Lynda Hall, Alan Mowlem, A Guide to Laboratory Animal Technology, page 56
2. (countable) A controlled regimen of food and drink, as to gain or lose weight or otherwise influence health.
3. (by extension) Any habitual intake or consumption.
   He's been reading a steady diet of nonfiction for the last several years.
   Last week the aging video game retailer emerged as the hottest stock on Wall Street, a story just unexpected and absurd enough to fill the new Trump-shaped void in our nation’s media diet. 2021-02-03, Farhad Manjoo, “Can We Please Stop Talking About Stocks, Please?”, in The New York Times, →ISSN

adj

1. (of a food or beverage) Containing less fat, salt, sugar, or calories than normal, or claimed to have such.
   diet soda
   Many grocery chains offer premium-priced lean or diet hamburger; but the fat content is usually at least 10 percent, sometimes 15 percent or more. 1982, Consumer Guide, Dieter's Complete Guide to Calories, Carbohydrates, Sodiums, Fats & Cholesterol, page 18
   The difference in weight (mass) of the regular and the diet drink of the same brand roughly equals to the amount of sugar in the regular drink. 1998, Andy Sae, Chemical Magic from the Grocery Store
   Diet Light (Pizarro 724; snacks S2-7; 9:30am-10pm) This perennially busy place serves not-very-diet, but yummy nonetheless, ice cream (S2 to S5) and whopping servings of mixed fruit (S3) – with ice cream. 2010, Lonely Planet Peru, page 347
2. (informal, figurative) Having certain traits subtracted.
   You folks reduce it to the bible only as being authoritative, impoverishing the faith. "Christianity Lite", diet Christianity for those who can't handle the Whole Meal.

Etymology 2

From Middle English dieten, dyeten, diȝeten, from Old French dïeter and Medieval Latin diētāre.

verb

1. (transitive) To regulate the food of (someone); to put on a diet.
   they will diet themselves, feed and live alone.
   When all signs of effusion, dulness, pain, œgophony, and cough had disappeared he was dieted, stimulated, and tonicked. 1887, Medical Press and Circular, volume 94, page 461
   As illustrating the belief that the Baptism by Blood was accompanied by a real regeneration of the devotee, Frazer quotes an ancient writer who says that for some time after the ceremony the fiction of a new birth was kept up by dieting the devotee on milk, like a new-born babe. 1920, Edward Carpenter, Pagan and Christian Creeds, New York: Harcourt, Brace and Co., published 1921, page 45
2. (intransitive) To modify one's food and beverage intake so as to decrease or increase body weight or influence health.
   I've been dieting for six months, and have lost some weight.
3. (obsolete) To eat; to take one's meals.
4. (obsolete, transitive) To cause to take food; to feed.

Etymology 3

From Middle English diet, dyet, from Old French diete, from Medieval Latin diēta, diaeta (“a public assembly; set day of trial; a day's journey”), from Ancient Greek δῐ́αιτα (díaita, “way of living, living space; decision, judgement”), influenced by Latin diēs (“day”).

noun

1. (usually capitalized as a proper noun) A council or assembly of leaders; a formal deliberative assembly.
   They were given representation of some important diet committees.
   The National Diet of Japan
2. (Scotland) A session of exams
   Normally the diet begins towards the end of April. “Coronavirus: School exam timetable could be put back next year”, in BBC News website, BBC, 3333-06-14, retrieved 3333-06-23
3. (Scotland, law) A criminal proceeding in court.
4. (Scotland) A clerical or ecclesiastical function in Scotland.
   a diet of worship