What do you think of this fact?
You flex your biceps, and something round bulges up under your skin and shifts around a little. To the ancient Romans, that looked like a little mouse scurrying around beneath the skin. And that’s exactly where the muscle got its name.
The mouse in your arm
The Latin word “mus” means mouse. Add a little diminutive ending and you get “musculus,” meaning “little mouse.” The Romans used that very same word for muscles. According to Merriam-Webster, arm and leg muscles in particular reminded them of mice, and Etymonline singles out the biceps.
But why? The DWDS, the big digital dictionary of the German language, offers two possible explanations. Either the twitching and gliding under the skin looked like a running mouse, or the oval, rounded shape of a muscle resembled the body of a small rodent. Maybe it was both.
Not just the Romans
Others had the same idea. In Ancient Greek, according to Etymonline, the word “mys” meant both mouse and muscle. And in Cornish, a Celtic language from Cornwall, one muscle was literally called “mouse of the leg.” So several languages looked at muscles and thought of rodents. Pretty bizarre.
“Muscle” made its way into English in the 14th century. German only picked up “Muskel” in the early 18th century, according to the DWDS, as a scholarly loanword from medical Latin.
The mussel is in on it too: according to Etymonline, the shellfish’s name also goes back to “musculus,” the little mouse.
From mouse to might
In English, the word kept evolving. Since the 19th century, “muscle” has also meant strength and power, as in “political muscle.” According to Etymonline, the “muscle car” showed up in 1969, all horsepower and attitude. That’s a lot of power for a word that started out as a small rodent.
So every time you hit the gym to build muscle, you’re technically raising mice.