found: LC database, 12-1-94(usage: Ninja; Ninjas)
found: Random House(Ninja)
found: World Book:under Martial arts (Ninja)
found: Hennepin(Ninja)
found: Amer. heritage dict.(Ninja; pl. Ninja or Ninjas)
found: Kodansha encyc. of Japan:under ninjutsu (ninja)
found: Merriam-Webster dictionary online, Oct. 26, 2016(ninja plural ninja also ninjas : a person trained in ancient Japanese martial arts and employed especially for espionage and assassinations)
found: Dictionary.com unabridged, Oct. 26, 2016(ninja plural ninja, ninjas: a member of a feudal Japanese society of mercenary agents, highly trained in martial arts and stealth (ninjutsu) who were hired for covert purposes ranging from espionage to sabotage and assassination)
found: American heritage dictionary of the English language, ©2016, via TheFreeDictionary website, Oct. 26, 2016(ninja pl. ninja or ninjas: A member of a class of medieval Japanese mercenary agents who were trained in the martial arts and hired for covert operations such as assassination and sabotage)
found: Wikipedia, Oct. 26, 2016(A ninja (忍者) or shinobi (忍び) was a covert agent or mercenary in feudal Japan. The functions of the ninja included espionage, sabotage, infiltration, assassination and guerrilla warfare. Their covert methods of waging irregular warfare were deemed "dishonorable" and "beneath" the samurai-caste, who observed strict rules about honor and combat. The shinobi proper, a specially trained group of spies and mercenaries, appeared in the 15th century during the Sengoku period, but antecedents may have existed in the 14th century, and possibly in the 12th century (Heian or early Kamakura era); Ninja is an on'yomi (Early Middle Chinese-influenced) reading of the two kanji "忍者". In the native kun'yomi kanji reading, it is pronounced shinobi, a shortened form of the transcription shinobi-no-mono (忍の者); In the West, the word ninja became more prevalent than shinobi in the post-World War II culture, possibly because it was more comfortable for Western speakers. In English, the plural of ninja can be either unchanged as ninja, reflecting the Japanese language's lack of grammatical number, or the regular English plural ninjas)
found: Levy, J. Ninja, 2008, via Google books, viewed Oct. 26, 2016:p. 12 (The word "ninja" comes from two kanji characters; in the Chinese-derived pronunciation, the characters are read as nin and sha, giving the compound word "ninja"; in the Japanese pronunciation, they give the words shinobi and mono, which, when put together, imply a linking word, no, so that they read as shinobi no mono; many translations from Japanese sources use the words shinobi or shinobi no mono interchangeably with the word "ninja," but in the West the shorter, easier term is the one that caught on)
found: Cummins, A. Samurai and ninja, 2015, via Google books, viewed Oct. 26, 2016:p. 16 (The term ninja is traditionally read as shinobi no mono; the term shinobi no mono is often shortened; ninja was pronounced shinobi no mono or just shinobi)
found: Ninja encyclopedia, via WWW, Oct. 26, 2016(Ninjas (忍者) refers to the group of professional spies who flourished in the pre modern age in Japan; ninjas entered into enemy territories in secret and they ran away with top secrets of their enemies; Ninjas were spies, they had lots of opportunities to come across their various enemies and fight with them. So, of course ninjas acquired many martial arts; If a ninja were to carry out the assassination of a lord of his enemy, he would carry it out secretly without being seen. In such a situation, the ninja wouldn't even have to use martial arts; Ninjas were professionals of espionage, destruction, assassination, and so on)
