ninja

1. One trained in ninjutsu, especially one used for espionage, assassination, and other tasks requiring stealth during Japan's shogunate period. · He used to work in the Japanese agency as a ninja.
2. One who very skillful, considered similar to the historical ninja, especially in covert or stealthy operation. (figuratively)
3. A notional draconian arm of a corporation (originally Nintendo), tasked with dealing with individuals that infringe on its rights or do not comply with its regulations. (figuratively, slang)
4. A programmer or tech worker, particularly one skilled in a particular programming language or environment; used especially in job adverts. (dated, figuratively, informal)
5. One who is considered to resemble the historical ninja in some way. (figuratively)
6. An amateur private miner in Mongolia. (figuratively, slang)
7. Synonym of nigga, used as a friendly term of address.
8. Synonym of man; used as a friendly term of address. · What up, my ninja!

Plural ninja