Real Dictionary

leech
countable noun: A leech is a small animal which looks like a worm and lives in water. Leeches feed by attaching themselves to other animals and sucking their blood.
countable noun: If you describe someone as a leech, you disapprove of them because they deliberately depend on other people, often making money out of them.

leech in American English 1
a physician
to act as a parasite
to heal
intransitive verb: to hang on to a person in the manner of a leech
noun: any bloodsucking or carnivorous aquatic or terrestrial worm of the class Hirudinea, certain freshwater species of which were formerly much used in medicine for bloodletting
transitive verb: to apply leeches to, so as to bleed

leech in American English 2
the after edge of a fore-and-aft sail
noun: a physician

leech in American English 3
noun: either of the lateral edges of a square sail

leech in British English 1
noun: any annelid worm of the class Hirudinea, which have a sucker at each end of the body and feed on the blood or tissues of other animals

leech in British English 2
noun: the after edge of a fore-and-aft sail or either of the vertical edges of a squaresail