- diet (1)
- "regular food," early 13c., from O.Fr. diete, from M.L. dieta "parliamentary assembly," also "a day's work, diet, daily food allowance," from L. diaeta "prescribed way of life," from Gk. diaita, originally "way of life, regimen, dwelling," from diaitasthai "lead one's life," and from diaitan, originally "separate, select" (food and drink), freq. of *diainysthai "take apart," from dia- "apart" + ainysthai "take," from PIE base *ai- "to give, allot." Often with a sense of restriction since 14c.; hence put (someone) on a diet (mid-15c.). The verb meaning "to regulate oneself as to food" (especially against fatness) is from 1650s. An obsolete word for this is banting. The adj. in this sense (Diet Coke, etc.) is from 1963, originally Amer.Eng.
- diet (2)
- "assembly," c.1450, from M.L. dieta, var. of diaeta "daily office (of the Church), daily duty, assembly, meeting of counselors," from Gk. diaita (see diet (1)), but assoc. with L. dies "day" (see diurnal).