Whenever someone asks me if I got a haircut, I always reply "actually, I got all of them cut;" or if someone mentions going for a haircut, I ask "oh really, which one?" It's a dumb old dad joke I know.
But it got me thinking ... I realize that there aren't many cases where a noun form can mean either a singular instance, or all of it, but 'hair' happens to be just such a case.
Singular: I plucked a (single) hair.
Plural: I lost two hairs.
???: I got (all) my hair cut.
I was wondering whether there is a specific grammatical term for this "third" amount-specifier?