moccasin (n.)

1610s, foot-covering worn originally by native North American people (made of deerskin or soft leather and without a stiff sole), from an Algonquian language of Virginia, probably Powhatan makasin "shoe," from Central Atlantic Coast Algonquian *mockasin, which is similar to Southern New England Algonquian *makkusin, Munsee Delaware mahkusin, Ojibwa makizin. Related: Moccasined.

As a name for a type of venomous snake of the southern U.S. (1784), it is perhaps a different word, but none has been found to match it. Bright regards them as identical, but the sense connection is difficult to explain.