Main Entry: mus·sel

Pronunciation: \ˈmə-səl\

Function: noun

Etymology: Middle English muscle, from Old English muscelle, from Vulgar Latin *muscula, from Latin musculus muscle, mussel

Date: before 12th century

1 : a marine bivalve mollusk (especially genus Mytilus) usually having a dark elongated shell
2 : a freshwater bivalve mollusk (as of Unio, Anodonta, or related genera) that is especially abundant in rivers of the central United States and has a shell with a lustrous nacreous lining