[AS. Iaccan.] A worm-like animal possessing one or two sucking discs. It is found in fresh and salt water, and sometimes on land. The medicinal leech is from 2 to 3 inches in length, with a minutely-ringed body, composed . of 102 skin rings, and has a sucker moved by strong muscles. This species of leech is largely used in abstracting blood from the body for medical purposes.