What word does your mother always say?
Old English fætt "fat, fatted, plump, obese," originally a contracted past participle of fættian "to cram, stuff," from Proto-Germanic *faitaz "fat" (cf. Old Frisian fatt, Old Norse feitr, Dutch vet, German feist), from PIE *poid- "to abound in water, milk, fat, etc." (cf. Greek piduein "to gush forth"), from root *peie- "to be fat, swell" (cf. Sanskrit payate "swells, exuberates," pituh "juice, sap, resin;" Lithuanian pienas "milk;" Greek pion "fat, wealthy;" Latin pinguis "fat").
Teen slang meaning "attractive, up to date" (also later phat) is attested from 1951. Fat cat "privileged and rich person" is from 1928; fat chance "no chance at all" attested from 1906. Fathead is from 1842; fat-witted is from 1590s; fatso is first recorded 1944. Expression the fat is in the fire originally meant "the plan has failed" (1560s).
mid-14c.; see fat (v.). Figurative sense of "best or most rewarding part" is from 1560s.
Any of various soft, solid, or semisolid organic compounds constituting the esters of glycerol and fatty acids and their associated organic groups.
A mixture of such compounds occurring widely in organic tissue, especially in the adipose tissue of animals and in the seeds, nuts, and fruits of plants.
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. See more at saturated fat, unsaturated fat.
(Heb. heleb) denotes the richest part of the animal, or the fattest of the flock, in the account of Abel's sacrifice (Gen. 4:4). It sometimes denotes the best of any production (Gen. 45:18; Num. 18:12; Ps. 81:16; 147:47). The fat of sacrifices was to be burned (Lev. 3:9-11; 4:8; 7:3; 8:25; Num. 18:17. Comp. Ex. 29:13-22; Lev. 3:3-5). It is used figuratively for a dull, stupid state of mind (Ps 17:10). In Joel 2:24 the word is equivalent to "vat," a vessel. The hebrew word here thus rendered is elsewhere rendered "wine-fat" and "press-fat" (Hag. 2:16; Isa. 63:2).