If any category of words is especially prone to extinction, it is those relating to measures. Words that relate to things, like sky or egg, tend to persist because the things themselves usually continue to exist; likewise, words that relate to ideas, like freedom or evil, persist because people continue to debate them. Measures, however—whether of liquids, solids, length, or area—are neither “things” nor “ideas,” and the moment they cease to serve a purpose they become mere nuisances and are duly forgotten. The word nipperkin, for example, is now almost unknown, but there was a period of several hundred years, after it first appeared in English in the late seventeenth century, when nipperkin was probably spoken tens of thousands of times each day in London alone. The word referred to a standard measure of liquor: about half a pint, the amount that you could drink if you were to “nip in” for a quick one on the way home. Both this nip—the one in the phrase to nip in—and the one in a nip of whiskey are the only remaining vestiges of nipperkin. The word derived from the Dutch word nypelkin, the kin being a diminutive meaning little, but no one is sure what a nypel was or why you would want a little one. The same diminutive ending appears in firkin, a cask containing about eight gallons, and in kilderkin, a cask containing about eighteen gallons. With these two words, the first half of the name represents a fraction: the fir of firkin, for example, derives from an old Dutch word that meant a fourth because a firkin was one fourth of a barrel; likewise, the kilder of kilderkin derives from an old Dutch word that meant a fifth because the kilderkin was one fifth of a tun, a tun being a barrel of about 250 gallons. A firkin, incidentally, tended to be used only for measuring butter; today selling butter by the firkin would be impractical: a single one would cost about $167.00 and would take up the entire refrigerator. The fifteenth-century measure known as the tierce also derives its name from a fraction—the Latin tertius, meaning a third—because it was one third of a pipe,which is equal to one half of a tun, two hogsheads, four barrels, or 105 gallons. The much older measure called the sester, dating back to the eleventh century, derives its name from being a sixth of a congius (a congius, as you know, being one eighth of an amphora). Other measures, such as the amphora, have taken their name from their shape: amphora derives from the Greek amphoreos, meaning two-handles. Similarly, runlet, the name of a medieval wine cask containing about eighteen gallons, originated as the diminutive of the French ronde, meaning round (although it is unclear why the roundness of the runlet was more remarkable than mat of any other cask or barrel). Sometimes, instead of becoming defunct, the name of a measure came to mean something new: a muid—which takes its name from the Latin modius, meaning measure—was originally a cask of about sixty gallons, but eventually came to mean the area of land that could be sowed with a muid of seed. Finally, some measures seem to have been doomed to obsolescence by their very specificity: the cran, whose name comes from a Gaelic source meaning a share, was used only to measure fresh herring; in 1816 the Commissioners for the Herring Fishery fixed a cran at 42 gallons but this was raised in 1832 to 45 gallons, the equivalent of about 750 fresh herring.