As liquids used in cooking go, vinegar is not particularly remarkable. It’s basically diluted acetic acid. The interesting aspect of vinegar is the enormous variety of ways you can make it.
The word “vinegar” came originally from Old French (“van egre”) in the early 1300s. One of the oldest surviving mentions of “vinegar” is from Piers Plowman, the Middle English allegory by William Langland, written around 1380 or so: “…vinegre, I trouwe, Walleþ in my wombe.” Even in those days, the different methods of making it were reflected in what it was called. There was “wine vinegar”, “malt vinegar”, “sugar vinegar”, and “wood vinegar”.
There were also some less common (and thus probably more interesting) sorts. “Radical vinegar”, which was also called “radicated” vinegar, was a particularly concentrated form that is today known chemically as “glacial acetic acid”. And even if you were a law-abiding cook, you might use “thieves’ vinegar”, which was vinegar with rosemary leaves, sage, and some other miscellaneous herbs — this stuff must have been highly aromatic, and was thought to be an antidote for plague.
As you might guess, there’s a story behind the name “thieves’ vinegar.” Actually several stories. All of the versions of the story feature an outbreak of plague, usually either in Marseille or Toulouse, and a gang of thieves was either caught robbing sick and dead victims, or maybe they had been caught before the disease arrived and sentenced to bury the dead — but the key is that these thieves, for some reason, seemed to be immune to the plague. Their secret was this kind of vinegar, which (depending on the story) they had either come up with themselves or had stolen from — well, somebody.
Traditionally “thieves’ vinegar” was more formally known as “four thieves’ vinegar.” That either refers to the size of the gang, or possibly suggests that the real name of the stuff was “Forthave’s vinegar” because it was first concocted by Richard Forthave. On the other hand, there’s a 1741 book called “Abregé de tout la m´decine practique” that claims it wasn’t Forthave, but George Bate who first created it. Bate was a physician to the English royal court in the 1600s — among other things he treated both Charles I and Oliver Cromwell, and was one of the founders of the Royal Society.
The linguistic variations of “vinegar” weren’t limited to compounds like “radical vinegar” and “thieves’ vinegar”. There are also a couple of words that incorporate some of the vinegar sources. “Alegar” was a word that appeared around 1500 and describes a kind of very pungent vinegar made from sour beer (not, despite the name, from ale). And “beeregar”, a more obscure word, has to do with more or less the same thing. “Beeregar” seems to have disappeared from usage toward the end of the 1800s, but “alegar” is still in use. But not in the US — around here we’ve always just called that stuff “malt vinegar,” even though that itself is not the most common sort of vinegar.
The reason you’d use a word like “alegar” or “beeregar” is, of course, because the word “vinegar” suggests that the stuff is made from wine (“vin-”). That’s also from a French root, and both that root word and wine itself are woven so deeply into English and European culture that if you see nearly any English word beginning with “vin” you might well discover that it, too, has some connection to wine. “Vinolent”, for example, sounds like it might have to do with violence, but it doesn’t. It just means drinking too much wine. Chaucer used it, and translated into modern English he wrote “In woman vinolent is no defence, This knowen lecchours by experience.” “Vinolent” has always been obscure (even more so than “beeregar”), but Aldous Huxley revived it in “Mortal Coils” in 1921: “By half-past nine a kinder vinolent atmosphere had put to sleep the hatreds and suspicions of before dinner.” Even alegar wouldn’t give you that sort of atmosphere.
