What's dressed in all black, practices stealth, and is a master of espionage, sabotage, and assassination? You guessed it: it's a ninja! Perhaps the only thing more elusive than a ninja is the source of the word ninja. In Japan ninja are more often referred to as shinobi. The word shinobi, short for shinobi-no-mono, means "to steal away." The word shinobi appears in poems as far back as the eighth century. So how did this word become ninja? Some believe that during the Edo period in Japan, the word shinobi-nomono was appropriated and transformed to the very similar word ninja. This probably happened because it was a lot quicker and easier to just say ninja. It is difficult to see how such a transformation could have occurred when we look at the words using the English alphabet, but if you could see the words written in Japanese, you would see that they are quite similar.