Here we are coming up on the New Year, and, having overindulged over the holidays, many a hopeful person makes a Resolution to lose some fat in the coming year. Nowadays we tend to think of fat as a bad thing best avoided. We divide up fats according to whether they're good or bad for our health: trans-fats, saturated fats, omega 3 fats… But English has many words for fats, and they tell us a lot about how we viewed fat in past centuries.
fat - Let's start with the word fat itself. This word has been with us since Old English, keeping a stable meaning all this time. But some of the metaphorical uses of the word are more revealing. For example, think of the phrase living off the fat of the land, in which fat means the richest and best part. We didn't always think fat was such a bad thing.
suet - hard fatty tissue about the loins and kidneys of beef, sheep, etc.
tallow - hard rendered fat of sheep and cattle, used to make candles and soap
lard - rendered fat of hogs, especially internal fat of the abdomen (also v. adding fat (or, metaphorically, something else) into something) (Ultimately derived from Latin for bacon)
schmaltz - rendered chicken, goose, (or pork) fat, especially in German and Ashkenazi Jewish cuisine (from German, entered English via Yiddish, cognate with melt)
Having lots of different words for different varieties of something is always a good clue that that something is important in a culture. Traditionally, fat was an important source of energy for hard work - calories in a world where people weren't constantly getting more calories than they needed. Fat was also considered a delicious boost of flavor for any recipe. Consider the process of larding lean meat with fat… nowadays we work hard to trim the fat out of the meat, but the verb lard comes from a time when people worked to put more fat in.
Since the 1930's schmaltz has meant excessive sentimentality, presumably as in too much of a good thing. An idiom falling into the schmaltz pot meant receiving a stroke of good luck.
Note that the different words for fat above are divided not by their health affects as we tend to do nowadays, but according to where the fat comes from and how you use it, which tells you what was important to people then.
shortening - fat that is solid at room temperature used to make pastry or bread. Shortening is something that shortens dough, and "short" dough is crumbly or friable, whereas "long" dough is stretchier. (The OED lists its first use of shortening in 1823 and relates it to the sense of shorter fibers. Some sources, however, give the word an older birthdate and attribute it to an entirely different root meaning weak or timid. Believe whom you will.)
blubber - layer of fat below the skin of a whale or other large marine mammal (derived, apparently, as an imitative version of a Middle English word for bubble.) Allegedly blubber is high in "good" fats and low in the "bad" fats, and tastes like arrowroot biscuits.
Words for fat on people would, of course, be an entirely different list of words, all with their own slightly differing derivations and connotations. Maybe losing some fat in 2012 would be a healthy resolution for some, but not for the English language. I hope we don't trim the fat there!
[Picture: Jack Sprat and His Wife, Rosie, rubber block print by AEGN, 2001.]