The term great sword refers to any of a number of large two-handed swords used in medieval Europe. This should not be confused with its descendant, the sword that is called a true two-handed sword from the Renaissance. While there is some overlap in terms as great swords are sometimes (correctly) called "two-handed swords", it is not historically correct to refer to all "two-handed swords" as great swords.

These swords were for the most part scaled-up versions of the contemporary long-sword with size being the main distinction: both were considered war swords but the great sword could not be used with one hand. These were exclusively infantry weapons and could not be used in conjunction with a shield. While terms do overlap, it is certain that great swords usually sported longer, heavier blades. Even 18th century broad swords - the curved-blade variety, akin to a thick sabre - could be referred to as great swords, though the term is used nearly exclusively for straight two-handed swords of the late Middle Ages and the Renaissance. Therefore, great sword is best regarded as a generic term, and it is important to remember that great is relative.

Dating to at least the 13th century these early swords often had flat wide blades, while later examples were either diamond or hexagonal in cross section. This was in response to better plate armor, and was used more for thrusting than for hacking. Some of these later versions were considered bastard-swords. There are surviving examples with blades 4 feet long, and with hilts longer than 16 inches.

Types of great sword include:

• Spadone
• Rhenish Langenschwert