A heavy iron hook or V-shaped arm attached to the side door of a Railway Post Office car. The clerk would swing the arm outward as the train passed a station to snag a suspended pouch of outgoing mail, while simultaneously kicking out the incoming mail pouch onto the platform.
Heard on the job
Keep your head inside the window, you don't want to get clipped by the mailcatcher when we pass the depot.
Also heard as
- mail hook
- catcher arm