The revolver's name is almost too plain to notice. It is a gun named after the motion of one of its parts, and that part was not originally the one people picture.
Etymonline dates revolver to 1835, as a "revolving firearm," a pistol that could fire several shots without reloading. It is an agent noun formed from revolve. Samuel Colt named it for its "revolving bored barrel," Etymonline says. Later models used a revolving cylinder of chambers instead.
The verb is much older. English had revolve by the late 1300s, from Old French and directly from Latin revolvere, "to roll back, unroll." That is re-, "back, again," plus volvere, "to roll." In English the verb first meant to change direction. The sense of a planet circling a fixed point came in 1713, and rotating on an axis in 1738.
The idea of a revolving gun came before Colt. Britannica notes pistols with revolving cylinders as early as the 17th century, along with "pepperboxes" whose several barrels turned as one unit. Britannica says the principle became truly successful as a practical weapon only in 1835 and 1836, when Colt patented his version.
The Lemelson-MIT Program tells Colt's story. At 15 he sailed to India as a deckhand. The repeating gun is said to have come to him on that voyage, perhaps inspired by the ship's capstan. He received a U.S. patent for a six-shot revolver in 1836.
Success was slow. Colt founded the Patent Arms Manufacturing company in Paterson, New Jersey, in 1837, but sales were poor and the factory closed in 1842. War revived the business. In 1846, after Texas Rangers reported on his guns, the government ordered 1,000 improved "Walker" pistols. By 1856 Colt was among the wealthiest businessmen in America.
The Latin volvere sits behind a large family of English words. Etymonline connects revolt, revolution, volume and evolve to the same root, meaning "to turn" or "to roll."