Since when did all clothing items become singular?

Question

I was watching "What Not To Wear" a while ago and it drove me crazy that they kept saying "a pant", "a jean", "a boot" instead of "pants", "jeans", "boots", etc.

Since then I've noticed one or two other people saying it too. It sounds weird to me, especially with the boots and shoes, because unless you only have one leg, you're wearing two of them!

Is this some sort of recent phenomenon? Is it correct?

Since you'd say "A pair of jeans", doesn't that imply that they are plural?

Answer 1

when its plural it refers to both parts. when its singular it refers to it as one pair. ex. jean = one pair. jeans=2 legs. boot=one pair. boots=2 shoes.