The long katana is often referred to as an ōdachi or nodachi. Both terms are used to describe a type of Japanese sword with an exceptionally long blade. The terms ōdachi and nodachi are sometimes used interchangeably, though some people differentiate between them based on certain characteristics.

The ōdachi generally refers to a large sword with a blade length exceeding 90 centimeters (35 inches) and often surpassing 120 centimeters (47 inches). It was primarily used by skilled samurai warriors on the battlefield for its extended reach and cutting power. The ōdachi is also sometimes called a "great sword" or "long sword."

On the other hand, the term nodachi can be used more broadly to describe any type of field sword or large sword. It can encompass swords with various lengths and shapes, including those that fall within the ōdachi category.

While there can be some variation in the use of these terms, both ōdachi and nodachi generally refer to longer-than-average katanas or other large swords. These weapons were less common compared to standard-sized katanas and were primarily utilized by skilled warriors in specific historical contexts.