No, a kodachi is not a katana, but it shares similarities in terms of design and construction. The kodachi is a distinct type of Japanese sword, and while it is related to the katana, there are differences between the two.

The main difference between a kodachi and a katana lies in their size and length. A kodachi is generally shorter than a standard katana but longer than a tanto. The typical blade length of a kodachi is between 50 to 60 centimeters (20 to 24 inches), while a katana typically has a longer blade ranging from 60 to 80 centimeters (24 to 31 inches).

Additionally, the intended use and historical context of the kodachi differ from that of the katana. The kodachi was primarily used as a close-quarters combat weapon, ideal for swift and agile fighting, while the katana was the primary battlefield weapon of the samurai, suitable for both cutting and thrusting techniques.

However, it's worth noting that the terminology and categorization of Japanese swords can vary, and there might be some overlap or regional variations in the use of terms. The distinction between a kodachi and a katana can sometimes be blurred or ambiguous depending on the specific historical period or regional traditions.

In summary, while the kodachi shares design elements with the katana, it is a distinct type of sword, typically smaller and used for different purposes in comparison to the katana.