Leech (noun)

1. A wormlike aquatic or terrestrial animal that sucks the blood of mammals, fish, or other animals.
2. A person who preys upon or clings to others for personal gain.

Origin:

Old english læce, from proto-germanic *laiks (compare old norse lækir, dutch leek, german laie "leech"), from pie root *leig- "to smear," with derivatives referring to sticky or adhesive substances (compare greek leichein "to smear," latin lingere "to lic.k")

Examples:

1. The leeches were used in the past for medicinal purposes to drain blood from the patient.
2. The leech attached itself to the side of the fish.
3. He was called a leech for always asking for money from his friends.
4. The leech is a parasitic animal that feeds on the blood of other animals.
5. He was a leech on society and never worked a day in his life.