忍 NIN – “Endurance, Patience”
You can gain a deeper understanding of the term Ninjutsu by taking a closer look at the Japanese character nin ( 忍 ). The kanji (Japanese character: (character: 忍 )) “NIN” means patience, endurance or secret. But it also means hidden, furtive, or to spot the hidden.
The character itself is composed of the two parts ken (sword or blade) and shin / kokoro (heart or spirit). It means that the heart has to guide the sword, or that the mind has to be as sharp as a blade. Therefore common translations of ninjutsu are “the Art of the Enduring Heart” or “the Hidden / Secret Art”.