Nine men's morris is a strategy board game for two players dating at least to the Roman Empire. The game is also known as nine-man morris, mill, mills, the mill game, merels, merrills, merelles, marelles, morelles, and ninepenny marl in English. The game has also been called cowboy checkers and is sometimes printed on the back of checkerboards. Nine men's morris is a solved game, that is, a game whose optimal strategy has been calculated. It has been shown that with perfect play from both players, the game results in a draw.
The Latin word merellus means 'gamepiece', which may have been corrupted in English to 'morris', while miles is Latin for soldier.
Three main alternative variations of the game are three, six, and twelve men's morris.