name

• (offensive, slang, ethnic slur) The Japanese language.
  "He petered out under Pitty's savage look: Do you speak Jap? Do you understand the world from inside those bastards' slanty-eyed little head-lopping poem-writing minds?"
• (informal, Hong Kong, Singapore, Australia) Clipping of Japanese.

noun

• (derogatory, ethnic slur, US) A Japanese person.
  "Among our Japs on board are two returning from Italy, where they have been with silk-worms' eggs, on cards, to sell. This has become a great speculation, and the Japs are going into it with zeal. The Japs almost always—always when they can—take cabin passages ; the Chinese seldom, or never."
• (derogatory, now historical, US) An Imperial Japanese Army soldier.
  "The Japs had been confident that this first and sudden land grab could be accomplished without their becoming involved in a major war, and they were right."

adj

• (derogatory, ethnic slur) Japanese; of or pertaining to Japan or its people.
  "A soldier might grab his rifle and batter his way to the heart of some Jap position. Back home they gave him all sorts of medals but his companions dismissed him as the poor bastard who finally went Asiatic."

verb

• (Canada, US, ethnic slur, slang, transitive) To carry out a sneak attack upon (something or somebody).