gangster

Short definition from Wiktionary

Noun

1. 1
   A member of a criminal or street gang.
2. 2
   A member of a professional criminal organization (in organized crime): a racketeer.

Verb

1. 1
   To act like a gangster; to commit street crime or run a racket.

Adjective

1. 1
   Characteristic of a gangster; (especially) admirable and audacious.
2. 2
   On friendly terms; cool.