Grist: Grain for grinding; ground grain. Unchanged in form and meaning since Old English; “perhaps related to grindan ‘to grind’ (see grind), though OED calls the connection ‘difficult’.” (Source: Online Etymology Dictionary.)* As Michael Qunion explains in World Wide Words, public grist mills were once common in Britain and the United States.**
In the 21st century we’re most likely to encounter grist, if we encounter it at all, in the idiom “grist for the mill,” which means “something that can be used to advantage,” as in grain that can be readied for flour. However, I recently saw the idiom rendered as “gist for the mill.” I dismissed it as a typo until I did a Google search and discovered more than 50,000 hits for gist for the mill.
There’s a podcast called Gist for the Mill, for example, whose title may be spelled that way for comic effect. (There’s a lot of humor on the site, and the forum section is called Gist Forum the Mill.) But I also found “some gist for the mill” in a Democratic Underground forum, “more gist for the mill” in a post on a Canadian political blog, and “provide gist for the mill” in a set of flashcards for the study of abnormal psychology.
One of George W. Bush’s Bushisms, first reported by Newsweek in 2000, was “I thought how proud I am to be standing up beside my dad. Never did it occur to me that he would become the gist for cartoonists.”
So it seems that a lot of people are substituting gist (the real point, the crux) for grist (grain) because they think it’s logical. In other words, they’re using a type of malapropism known as an eggcorn.
Gist is certainly more familiar than grist to modern-day, non-grain-grinding speakers of English. When gist and grist are pitted against each other in GoogleFight, the results are decisive.
Of course, the two words have different consonant sounds: the G in gist is /j/, while the G in grist is /g/. So I’m guessing that this particular eggcorn is based on mis-reading rather than mis-hearing. That is, if it’s an eggcorn at all: I couldn’t find it in the Eggcorn Database, which contains many examples of eggcorns based on mis-hearing: for all intensive purposes and minus well are among the most common.
Grist survives intact as the name of a nonprofit online magazine about environmental issues, founded in 1999. Grist’s news section is called Gristmill (“fresh, whole-brain news”); its pop-culture section is called GristList. Grist’s taglines are “A Beacon in the Smog” and “Gloom and Doom with a Sense of Humor.”
* Grist is not related, etymologically, to gristle, which has meant “cartilage” since Old English and which is related to West Germanic words such as crostila and gruschel.
** This entry also contains useful and entertaining information about millstone, keep one’s nose to the grindstone, and run of the mill.