- 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.
- A person trained primarily in <xref>stealth</xref>, <xref>espionage</xref>, <xref>assassination</xref> and the Japanese martial art of <xref>ninjutsu</xref>.
- A Mongolian amateurish private <xref>miner</xref> (mainly for gold); after the shape of the plastic <xref>bowls</xref> used to wash metal <xref>ore</xref> with <xref>mercury</xref>, roughly resembling one of the Teenage Mutant Ninja Turtles.
- <xref>Juggalo</xref> version of the epithet "<xref>nigga</xref>".
- To act in the manner of a ninja, especially in the areas of speed and power.
- To claim an item in a game by abusing game mechanics, often despite having no real need for the item or ability to use it.
- To post a response on a <xref>message board</xref> immediately before someone else unknowingly posts a response saying the same thing.
- a class of 14th century Japanese who were trained in martial arts and were hired for espionage and assassinations
- a member of the ninja who were trained in martial arts and hired for espionage or sabotage or assassinations; a person skilled in ninjutsu