A tsurugi (剣) is a Japanese sword, akin to the jian Chinese sword. The word is used in the West to refer to a specific type of Japanese straight, double-edged sword used in antiquity.
Kusanagi-no-Tsurugi
The current name for the sword which is one of the Three Imperial Regalia of Japan is "Kusanagi-no-Tsurugi".
References
Tsurugi (sword) Wikipedia(Text) CC BY-SA