Gladius is a Latin word for sword. Early ancient Roman swords were similar to those used by the Greeks. From the 3rd century BC, the Romans adopted swords similar to those used by the Celtiberians and others during the early part of the conquest of Hispania. This kind of sword was known as the Gladius Hispaniensis, or "Hispanic Sword." It was once thought that they were similar to the later Mainz types, but the evidence now suggests that this was not the case. Rather these early blades followed a slightly different pattern, being longer and narrower, and were probably those that Polybius considered good for both cut and thrust. Later extant Gladii are now known as the Mainz, Fulham and Pompei types. In the late Roman period Publius Flavius Vegetius Renatus refers to swords called semispathae (or semispathia) and spathae, for both of which he appears to consider gladius an appropriate term.
A fully-equipped Roman soldier would have been armed with a shield (scutum), several javelins (pila), a sword (gladius), probably a dagger (pugio) and perhaps a number of darts (plumbatae). Conventionally, the javelins would be thrown before engaging the enemy, at which point the gladius would be drawn. The soldier generally led with his shield and thrust with his sword. Despite the gladius being designed for thrusting at the enemy from behind the protection of the shield, all types of gladius appear to have been suitable for slashing and chopping motions.