What is the meaning of leech?

noun

• Carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end.
  • synonyms: bloodsucker, hirudinean
• A follower who hangs around a host (without benefit to the host) in hope of gain or advantage.
  • synonyms: parasite, sponge, sponger

verb

• Draw blood.
  • usage: "In the old days, doctors routinely bled patients as part of the treatment"
  • synonyms: bleed, phlebotomize, phlebotomise