a bloodsucking leech, Hirudo medicinalis, of Europe, introduced into the northeastern U.S., usually green with brown stripes, up to 4 inches (10 cm) long: once used by physicians to bleed patients.
Origin
1885-90
Examples from the web for medicinal leech
The same result has followed from keeping together different varieties of the medicinal leech.
British Dictionary definitions for medicinal leech
medicinal leech
noun
1.
a large European freshwater leech, Hirudo medicinalis, formerly used in medical bloodletting