Can we use these words interchangeably to mean ' a cover on something'?
This could get interesting:
pen -- cap
laundry hamper -- lid
toilet -- cover (the furry thing with elastic)
toilet -- lid (the hard thing attached with a hinge)
bottle -- cap
jar -- lid
mixing bowl, storage container -- cover
saucepan, casserole dish -- lid
gas tank -- cap
I have no idea what pattern or principle sorts them out...?