Jiu Jitsu, Ju Jitsu, Jutsu
the art of unarmed combat developed during the Edo period (1603-1868). Tradition has it that the word was invented by Sekiguchi Jushin.

Jo-jutsu
The art of fighting with a Jo, a wooden staff of 1.6 meter. Usually round, but sometimes hexagonal.

Jeet-Kune-Do
Kung-fu style developed by Bruce Lee.