old hat

[xyzzyplugh]

Where does this expression originate? Why a hat?

[Quizmonster]

There doesn't seem to be any particular reason why it's a hat; it might as well have been shoes, shirt or whatever. Certainly the first time it is recorded in print dates from 1911, in a sentence which referred to the idea of the devil having a trident as 'old hat'.

Here's my idea, though...in those days everybody wore a hat, of course, so perhaps that was the first item of clothing that might give away the fact that you were out of fashion. Presumably hat-styles altered more rapidly than suit-styles etc.

[xyzzyplugh]

I get it Quizmonster, a bit like, nowadays, we say it's pants.!?