The small sword or smallsword (also court sword, Gaelic: claidheamh beag or claybeg, French: épée de cour or dress sword) is a light one-handed sword designed for thrusting which evolved out of the longer and heavier rapier of the late Renaissance. The height of the small sword's popularity was between mid 17th and late 18th century, when any man, civilian or military, with pretensions to gentlemanly status would have worn a small sword on a daily basis.

The blade of a small sword is comparatively short at around 0.6 to 0.85 metres (24 to 33 in), though some reach over 0.9 metres (35 in). It usually tapers to a sharp point but may lack a cutting edge. It is typically triangular in cross-section, although some of the early examples still have the rhombic and spindle-shaped cross-sections inherited from older weapons, like the rapier. This triangular cross-section may be hollow ground for additional lightness. Many small swords of the period between the 17th and 18th centuries were found with colichemarde blades.

It is thought to have appeared in France and spread quickly across the rest of Europe. The small sword was the immediate predecessor of the French duelling sword (from which the épée developed) and its method of use—as typified in the works of such authors as Sieur de Liancour, Domenico Angelo, Monsieur J. Olivier, and Monsieur L'Abbat—developed into the techniques of the French classical school of fencing. The small sword could be a highly effective duelling weapon.

Militarily, small swords continued to be used as a standard sidearm for infantry officers. In some branches with strong traditions, this practice continues to the modern day, albeit for ceremonial and formal dress only. The carrying of swords by officers in combat conditions was frequent in World War I and still saw some practice in World War II. The 1913 U.S. Army Manual of Bayonet Drill includes instructions for how to defend against an opponent with a smallsword.

Bayonets of the period, such as the British Pattern 1907 bayonet, were relatively long with total lengths of 20 inches or more not uncommon. While a little larger, a smallsword could be carried in a very similar manner and would not appear out of place.