An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) A tissue composed of bundles of elongated cells capable of contraction and relaxation to produce movement in an organ or part.
2) An organ composed of muscle tissue (TheFreeDictionary.com).

From M.Fr. muscle "muscle, sinew" and directly from L. musculus "a muscle," literally "little mouse," diminutive of mus "mouse;" → -ule. So called because the shape and movement of some muscles (notably biceps) were thought to resemble mice.

Mâhice, literally "small fish, fish form," because of apparent resemblance of some muscles to fish, from mâhi, → fish, + -ce diminutive/similarity suffix; variant mâyce.