A bloodsucking aquatic or terrestrial worms typically having a sucker at each end: One of the leech species has been used in medical treatments to bleed patients or to eat away putrid flesh from a wound.

Leeches are any of numerous carnivorous or bloodsucking annelid worms that constitute the class Hirudinea, that typically have a flattened segmented lance-shaped body with well-marked external annulations (ringlike structures, segments, or parts), a sucker at each end, a mouth within the anterior sucker, and a large stomach with pouches of large capacity at the sides.

Such pouches are hermaphroditic (having both male female reproductive organs, usually with direct development, and which occur chiefly in fresh water, although a few are marine and some tropical forms are terrestrial.

A former name for a medical doctor: Sam read in an old book that the word leech used to refer to a ,medical practitioner or physician that came from an Old English word originally meaning "to pull".

The treatment of patients by the use of leeches: The leech therapy that Mrs. Smith received involved the bleeding of the affected part of her body by the use of leeches which resulted in curing her ailment. .

A nursing intervention from the Nursing Interventions Classification (NIC) defined as application of medicinal leeches to help drain replanted or transplanted tissue engorged with venous blood.

Thousands of patients currently owe the successful reattachment of body parts to miraculous technological advances in plastic and reconstructive surgery, however at least some of these operations might have failed if leeches had not been reintroduced into the operatng room. The appendages reattached include fingers, hands, toes, legs, ears, noses and scalps.

Outdated, the art of healing: In his old book on medicine, Mr. Hathaway read about leech-craf that was used to cure people possessing medical knowledge and skill.

A big European freshwater leech: Known as Hirudo medicinalis, the medicinal leech was formerly employed for the abstraction of small quantities of blood in inflammatory and other conditions.

Leeches were used as a method of bloodletting, a practice common up to the middle of the 19th century.

In modern times, leeches have been used to evacuate periorbital hemorrhage (black eye) and to remove congested venous blood from the suture lines of re-implanted fingers.

Sometimes, a patient's veins are too weak to carry blood and it builds up, causing "venous congestion" and since leeches are a source of hirudin, an anticoagulating principle secreted by their buccal glands and leech saliva contains several active substances including inhibitors of platelet aggregation, they are used to decrease such venous congestion.

The leech's saliva contains substances that anesthetize the wound area, dilate the blood vessels to increase blood flow, and prevent the blood from clotting and so attaching leeches to the body draws the blood away gradually and painlessly.

Leeches are particularly useful in plastic surgery; such as, breast reconstruction and where a part of the body has become severed and had to be sewn back on.