(1):

(n.) Any one of several fur-bearing carnivores of the genus Mustela, closely allied to the sable. Among the more important species are the European beech, or stone, marten (Mustela foina); the pine marten (M. martes); and the American marten, or sable (M. Americana), which some zoologists consider only a variety of the Russian sable.

(2):

(n.) The fur of the marten, used for hats, muffs, etc.

(3):

(n.) A bird. See Martin.