Language & words
The word muscle comes from the Latin for little mouse.
Musculus is the diminutive of mus, mouse. Romans apparently thought a flexing bicep looked like a small mouse moving under the skin.
Why is this true?
The same idea appears in Greek, where mys meant both mouse and muscle. Medical Latin kept the word, and it passed into most European languages.
More facts in this category
More about language & words
Language facts show how much of everyday speech is historical accident. Words that once meant the opposite, letters that vanished from the alphabet, punctuation with names almost nobody uses. Each entry explains the change that produced the oddity — a sound shift, a printing convention, a borrowing from another language — so it works as a genuine explanation and not just as a piece of trivia.