leech

Noun

• a follower who hangs around a host (without benefit to the host) in hope of gain or advantage

• carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end

Verb

• draw blood
  • In the old days, doctors routinely bled patients as part of the treatment
    

Related words

• Synonyms: 
  parasite , sponge , sponger , bloodsucker , hirudinean , bleed , phlebotomize , phlebotomise