Dictionary.com
definitions

medicinal leech

noun
  1. 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 of medicinal leech

First recorded in 1885–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for medicinal leech

medicinal leech

noun
  1. a large European freshwater leech, Hirudo medicinalis, formerly used in medical bloodletting
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012