Just across the road from our parish church is the old town lock-up, or clink, with the walled enclosure of the pound alongside it, now a private garden for the cottage next door. In earlier times this was the place where stray animals were brought to be kept safe until their owners could claim them by paying a fine. Such pounds went out of use in the nineteenth century because the law changed to permit the impounder of the animals to keep them on his own land, so there was no longer any need for a separate parish enclosure.
It’s still a common word, but this sense of pound is odd because it’s one of those mysterious words for which no sure origin can be found, a linguistic orphan. It’s recorded as far back as Middle English, but nobody has discovered a link to words in related languages. At one time it had the form pundfald or pundfold, and so is really the same word as pinfold and penfold, other names for the same thing. It’s also closely linked to pond, which comes from the related Old English word pyndan. The words pond and pound were often used interchangeably (which is why impound can have the sense of storing water in a reservoir). The other senses of the word — the unit of British currency, the unit of weight, and the verb to strike heavily — are all unconnected with it in their origins.
It looks as though compound in the sense of enclosure ought to be related, but it turns out it isn’t. Compound comes from the Malay word kampong, which arrived in English in the seventeenth century through Dutch. When people Anglicised its spelling, they may have had pound in mind or — more probably — the existing word compound, a thing composed of separate elements. This word had no connection with pound either, as it comes from the Latin componere via French compondre.
Modern pounds for the safe-keeping of animals don’t have the physical resonances of these old stone enclosures, but their name perpetuates this odd word history.