A saber is a curved sword with a single sharp edge, designed especially for slashing while on horseback. Unlike a straight sword meant for thrusting, a saber's curve helps a mounted soldier swing down and strike with devastating force. Cavalry officers in the American Civil War and European armies carried sabers as their primary weapons.

The word also refers to a type of sword used in modern fencing. The fencing saber is light and flexible, and competitors score points by hitting their opponent anywhere above the waist with either the edge or the flat of the blade. Fencing with sabers is faster and more aggressive than the other two types of fencing (foil and épée), since fencers can score with quick slashing motions instead of precise thrusts.

You might also see the word spelled sabre, particularly in British English. Both spellings are correct.

The phrase saber rattling means making threatening gestures or aggressive statements to intimidate others without actually fighting. When countries engage in saber rattling, they're showing off their military strength, hoping to scare opponents into backing down.