The rarely seen singular of the common trousers. I don't think anyone is quite sure what a trouser is, I'm certainly not. Is it one leg off the pair that together constitute a pair of trousers? If so, why do we feel the need to qualify when we say 'trouser leg?' Even when considering the familiar plural the confusion continues. Here in the US we call most trousers pants and only those pants on the more formal end of the spectrum do we actually use the word trousers, but this is far from universal. In the UK any and all of what we would call pants are strictly known as trousers and, in fact, pants is what they call the type of garment that we rather literally refer to as underwear. Though sometimes we do somewhat agree with those across the pond by calling them underpants and of course when those underpants in question belong to a female we drop the 'under' and tack on a jarring note of what I would call infantilization and refer to them as panties though this would sound strange to the rest of the Anglosphere who, seemingly just to add even more confusion to the mix, have plucked an entirely new word from the ether for these garments and call them knickers.