One of the most famous icons of Japanese martial arts is the ninja. The shadow warriors of ancient Japan have gained an almost supernatural image in recent times. Ninja were one of the greatest covert ops forces in history, but exactly who were they? And does reality match the striking image popular culture has created?

The word “ninja” as we know it is actually a rather recent term. Understanding it, though, first requires look at the Chinese writing system, which the Japanese system is based on. The Chinese word for ninja is 忍者, which Japanese pronounces as “ninja.” A lot of people will mistakenly tell you that the word means “invisible man,” but that’s a misconception. While the second character does roughly mean “person,” the first means “endure,” “spy,” or “hide.” Thus, the word ninja means “a person who endures or spies.”

But, in spoken Japanese, the word for “one who endures or hides” is actually “shinobi mono.” Usually it was shortened to just “shinobi.” This was the common word people used to refer to the clandestine warriors, not ninja.