Alex, The word is in the Oxford Dictionary under the spelling CAPEESH. "Capiche or Capeesh" is used chiefly in the Italian-American community. It became mainstream after Marlon Brando spoke it in the film 'The Godfather' in the 70's. The popular American television series 'The Sopranos' (2007) made liberal use of the word. Bart Simpson said it in a Simpson's episode. The word is part of the dialogue of many Hollwood movies. I have used it myself. So I would say that it is definitely in use in America. When a non-Italian employs the word, it invokes the strong bond that exist among members of the Italian-American immigrant community. It also brings to mind the Mafia. Beside the literal meaning of "Understand?" capiche has the subtext meaning of "You are one of us."

When foreign words are taken into English as slang, it's usually re-spelt. Another example is 'savvy' (as in "I'm in charge here, savvy?") comes from the French 'savez'. If you're not sure of a word and you think it might be foreign, just say it aloud and think of the sound instead of the spelling. You might just recognise it. Yes, it comes from the Italian 'capisci?'='you understand?' We also spell 'kapish' as 'capeesh'.

Hi... yes this word is not an english word... It is in fact an Italian word using by the mafia early in 1930... when the mafia patronizing the underworld...

No, this is not used in modern English. It is a slang term from years ago (1940s). It is used to ask "do you understand?" From what I know, it comes from the Italian verb "capisce" which literally means "you understand."