'mussel' originates from Middle English, specifically the word 'muscle', which came from the Latin word 'musculus', meaning 'little mouse', due to the shape of the shell resembling a mouse.

'musculus' transformed into the Old French word 'mouscle', and eventually became the modern English word 'mussel' through Middle English.

Initially, it referred to the shellfish itself, and this meaning has largely remained the same in modern usage.