Essentially the same as a geezer, but only in the American sense. An old and decrepit person, a clean version of "old fuck" or "old fart". Especially one who is cranky, eccentric or both. It is a derogatory term, but not horribly so. Unlike most similar terms it can apply to men or women; and elderly couple can be referred to as old fuds. Sometimes old fuds will even refer to themselves as old fuds, as if to say "I didn't die before I got old!"
Why is traffic so slow? It's that old fud with no place to go and all day to get there.
I got into a wreck with an old fud that shouldn't even be driving, can't see over the steering wheel.
For an old fud you move pretty well!