The word daito refers to Japanese long swords. Rather than a specific weapon, this is actually a class of blades under which both the katana and tachi fall. This term is often used interchangeably with either of the other sword names, and can be used to describe unspecific fake and practice Japanese-style swords. To qualify as a daitō the sword must have a blade longer than 2 shaku (24 inches) in a straight line.

On top of being made typically of longer straight-edged measure, the tachi also had a deeper curvature than the katana thus making the absolute length even more dissimilar. While there is a well defined lower-limit to the length of a daitō, the upper limit is not well enforced; as such swords that are longer "than normal daitō" are called odachi. Daitō is often used when explaining the similar terms shoto (short sword) and daisho (the set of both large and small sword).