also musk-rat, "large aquatic rodent of North America," 1610s, alteration (by association with musk and rat) of an Algonquian word (probably Powhatan), muscascus, literally "it is red," so called for its coloring. From cognate Abenaki moskwas comes variant form musquash (1620s). Dialectal mushrat is by 1890.
"large North American pike," 1789, from Algonquian (Ojibwa) maashkinoozhe; the second element is kinoozhe "pike;" the first is either mac "great," maazh- "similar to," or maazh- "ugly." Altered by French folk etymology as masque allongé "long mask." Called muskie for short (1889).