Parasite is a related term of bum.
As nouns the difference between parasite and bum
is that parasite
is (pejorative) a person who lives on other people's efforts or expense and gives little or nothing back while bum
is the buttocks or bum
can be (north america|colloquial) a hobo; a homeless person, usually a man or bum
can be (dated) a humming noise or bum
can be (obsolete) a bumbailiff.
As a verb bum is
(uk|transitive|colloquial) to sodomize; to engage in anal sex or bum
can be (colloquial) to ask someone to give one (something) for free; to beg for something or bum
can be to depress; to make unhappy or bum
can be to make a murmuring or humming sound.
As an interjection bum is
) an expression of annoyance.
As an adjective bum is
of poor quality or highly undesirable .