One who, or that which, rubs. Specifically:
(a)
An instrument or thing used in rubbing, polishing, or cleaning.
(b)
A coarse file, or the rough part of a file.
(c)
A whetstone; a rubstone.
(d)
An eraser, usually made of caoutchouc or a synthetic rubber(4).
(e)
The cushion of an electrical machine.
(f)
One who performs massage, especially in a Turkish bath.
(g)
Something that chafes or annoys; hence, something that grates on the feelings; a sarcasm; a rub.