leech in WordNet English dictionary

1. draw blood
   "In the old days, doctors routinely bled patients as part of the treatment"
   bleed  leech  phlebotomize  phlebotomise 
   

1. carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end
   leech  bloodsucker  hirudinean 
   
2. a follower who hangs around a host (without benefit to the host) in hope of gain or advantage
   leech  parasite  sponge  sponger