mussel

Etymology

From Middle English muscle (“mussel”), from Old English muscle, from Proto-West Germanic *muskulā, from Late Latin muscula, from Latin mūsculus (“mussel or muscle”, literally “little mouse”). Doublet of muscle.

noun

1. Any of several groups of bivalve shellfish with elongated, asymmetrical shells.
   1. A freshwater mussel, usually edible, of the order Unionida in subclass Palaeoheterodonta.
   2. A saltwater mussel, usually edible, of the order Mytilida in subclass Pteriomorphia.
   3. Any of certain other bivalves of somewhat similar appearance, such as the zebra mussel and quagga mussel of the family Dreissenidae in subclass Heterodonta.