Daishō (大小)—literally "big-little"—is Japanese for a matched pair of Japanese swords (nihonto) traditionally worn by the samurai class in feudal Japan.
A daishō is typically depicted as a katana and wakizashi mounted in matching koshirae but originally the daishō was the wearing of any long and short swords together. The katana/wakizashi pairing is not the only daishō combination as generally any longer sword paired with a shorter sword or a tantō is considered to be a daishō. Daishō eventually came to mean two swords having a matched set of fittings. A daishō could also have matching blades made by the same swordsmith, but this was in fact uncommon and not necessary for two swords to be considered to be a daishō, as it would have been more expensive.
The word daishō is derived from the terms daitō, meaning long sword, and shōtō, meaning short sword (daitō + shōtō = daishō).