leech

Short definition from Wiktionary

Noun

1. 1
   An aquatic blood-sucking annelid of subclass Hirudinea, especially Hirudo medicinalis.
2. 2
   A person who derives advantage from others in a parasitic fashion.
3. 3
   A glass tube designed for drawing blood from damaged tissue by means of a vacuum.
4. 4
   A physician.
5. 5
   A healer.
6. 6
   The vertical edge of a square sail.
7. 7
   The aft edge of a triangular sail.

Verb

1. 1
   To apply a leech medicinally, so that it sucks blood from the patient.
2. 2
   To drain (resources) without giving back.
3. 3
   To treat, cure or heal.

Proper noun

1. 1
   A surname originating as an occupation, derived from the profession leech, a former word for a physician.