means A handgun with a rotating cylinder that holds several bullets, letting the shooter fire multiple rounds before reloading.

from From the Latin 'revolvere,' to roll back or turn around — the same root that gives us 'revolve' and 'revolution.' The gun earned its name in the early 19th century from the very mechanism that defined it: a cylinder that revolves, bringing a fresh chamber into line with each pull. Samuel Colt's design popularized both the weapon and the word, so 'revolver' is quite literally named for the part that goes round and round.