As an adjective scrub
is mean; dirty; contemptible; scrubby.
As a noun scrub
is one who labors hard and lives meanly; a mean fellow or scrub
can be an instance of scrubbing.
As a verb scrub
is to rub hard; to wash with rubbing; usually, to rub with a wet brush, or with something coarse or rough, for the purpose of cleaning or brightening; as, to scrub a floor, a doorplate.
As an acronym soap is