To flog means to beat someone severely with a whip or stick as punishment. For centuries, flogging was used to punish sailors, soldiers, and prisoners. A captain might order a sailor flogged for disobedience, or a criminal might be flogged in the town square. Though this brutal practice is now illegal in most countries, you'll encounter it in historical novels and stories about the past.

The word also appears in the phrase flog a dead horse, which means to waste time and energy trying to revive something that's already finished, or to keep arguing about something that's already been settled. If your friend keeps complaining about a game your group played last week, wanting to replay it differently, you might think they're flogging a dead horse: the game is over, the outcome is set, and no amount of discussion will change it.

In British English, flog can also mean to sell something, usually in an informal or pushy way. Someone might try to flog their old bike at a yard sale.