Noun
tachi (plural tachi or tachis)
A pre-katana style Japanese sword.
An unsigned and shortened blade that was once made and intended for use as a tachi may be alternately mounted in tachi koshirae and katana koshirae. Source: Internet
"Igakusya tachi no sosiki hannzai kannto-gun 731 butai",Keiichi Tsuneishi The Emperor Hirohito did not admit deployment of biological weapon on the occasion of a report of President Staff Officer Umezu on October 25, 1944. Source: Internet
In the late 1500s and early 1600s many old surviving tachi blades were converted into katana by having their original tangs cut (o-suriage), the signature would be lost in this process. Source: Internet
Many longer tachi were shortened in the 15th–17th centuries to meet the demand for katana. Source: Internet
Signature and Date A pair of examples of chiseled signatures (mei) on the tangs of a katana (top); and tachi (bottom). Source: Internet
Since a tachi was worn cutting edge down, and the katana was worn cutting edge up the mei would be in opposite locations on the tang of both types of swords. Source: Internet