ninja

Etymology

A romanized borrowing of Japanese 忍者 (ninja), popularized within Japanese by manga after World War II and in English by Eric Van Lustbader's 1980 novel The Ninja and the 1981 movie Enter the Ninja, of uncertain derivation but with an underlying sense of secret or hidden person. The “Mongolian miner” sense arose from the supposed resemblance of the bowls used to wash ore with mercury to the shells of the Teenage Mutant Ninja Turtles. The Juggalo slang sense arose via influence from AAVE nigga.

noun

1. (martial arts) A person trained in ninjutsu, especially (historical) one used for espionage, assassination, and other tasks requiring stealth during Japan's shogunate period.
   The men... are now learning to be ninja or ‘stealers-in’. 1964, Ian Fleming, You Only Live Twice, page 126
   Spies prowled Japan from the seventh century, but the secretive ninja left few written records. October 15 2000, Denver Post, page 10
   Halo 2 is a lot like Halo 1, only it's Halo 1 on fire, going 130 miles per hour through a hospital zone, being chased by helicopters and ninjas. And, the ninjas are all on fire, too. 7 July 2004, Will Tuttle, quoting Jason Jones, “Halo 2 - Everything We Know!”, in GameSpy.com, archived from the original on 2021-11-10
2. (figurative) A person considered similarly skillful to the historical ninja, especially in covert or stealthy operation.
   For months the Japanese spoke of national-security adviser Henry Kissinger as a ninja—the magician of Japanese legends who performs supernatural acts and practices sorcery. 1972 September 11, Newsweek, Int'l ed., p. 28
   Other bankers are dubbing themselves ninja, modern-day descendants of the superspies of 17th century samurai houses. August 3 1987, Business Week, page 40
   Young banking and securities firms executives (nicknamed the ninja...) are especially assigned to cultivate relations with the finance ministry. Only verbal instructions are ever given to the ninja. August 4 1991, The Guardian, page 13
3. (figurative) A person considered to look like the historical ninja in some way, including (Mongolia, historical slang) amateur private miners.
   He immediately suspected they were ninjas because, he said, they were dressed in black and wore masks, trademarks of the mysterious assassins who have been sowing terror across East Java in recent months. December 28 1998, Chicago Tribune, page 1
   Yen buyers were more subdued... fearing the Bank of Japan's new strategy of covert intervention to buy U.S. dollars through agent banks—described by some as the central bank's ninjas or secret agents. February 21 2003, Business Times:
   Many were former nomads, but as the gold rush gathered pace, students, vets and taxi drivers from Ulan Bator joined the ninjas, not just in Ogoomor but in other gold towns across the country. October 10 2007, Jonathan Watts, “Prospectors and 'Ninja' Miners Flood to East's El Dorado”, in The Guardian
4. (African-American Vernacular) Synonym of nigga as a friendly term of address.
   LEPRECHAUN: What's up, ninjas? 2003, Leprechaun: Back 2 tha Hood (film)
   1. (Juggalo slang) Synonym of man as a friendly term of address.
      What up, my ninja!

adj

1. Of or related to ninjas in their various senses.
   The July 1966 issue had a cartoon concerning a Ninja dojo. 1966 October, Black Belt, page 5
   One of the most controversial characters in Japan's current ninja boom is a stout but surprisingly agile man in his mid-forties named Norihiro Iga-Hakuyusai. 1971 May, Black Belt, page 40
   […]Federal agents in body armor and black ninja uniforms[…] August 28 1995, Time, page 36
   As they broke camp, the teenage son practised his Ninja moves with a tentpole. August 31 2002, The Guardian, page 2

verb

1. (transitive, intransitive) To act or move like a ninja, particularly with regard to a combination of speed, power, and stealth.
   I leapt up, ninja'd over to Gav's bed and wheeched the duvet off. 1992, Iain Banks, Crow Road, page 160
   In our dark house we were ninja-ing around with water guns. April 23 1996, Rocky Mountain News, page 5
   I ninja'd my way into Kung Fu Records to hang out with those merry pranksters the Vandals. August 29 2002, Los Angeles Times, page 48
2. (Internet, slang) Synonym of preempt: to supersede and invalidate a response by posting immediately before it.
   When I hit post, I saw that Blue Emu had ninja'd me, so I just deleted my reply.
3. (online gaming slang) To claim an item through abuse of game mechanics.
   That damn warrior ninja'd an epic-quality wand even though he can't even use it!