Gladius is a Latin word properly referring to the type of sword that was used by ancient Roman foot soldiers starting from the 3rd century BC and until the 3rd century AD. Linguistically, within Latin, the word also came to mean "sword", regardless of the type used.

A sword is an edged, bladed weapon intended for manual cutting or thrusting. Its blade, longer than a knife or dagger, is attached to a hilt and can be straight or curved. A thrusting sword tends to have a straighter blade with a pointed tip. A slashing sword is more likely to be curved and to have a sharpened cutting edge on one or both sides of the blade. Many swords are designed for both thrusting and slashing. The precise definition of a sword varies by historical epoch and geographic region.