As a Noun: 1. Behaviour that is not polite. English = rudeness, impoliteness. 2. Language and behaviour that are likely to embarrass or offend people because they relate to sex or other bodily functions. English = rudeness. As a Verb or Adjective: 1. To behave in a way that is not polite. English = (be) rude, (be) impolite. 2. Of language and behaviour, to be likely to embarrass or offend people because they relate to sex or other bodily functions. English = (be) rude. 3. To behave in a bad-mannered, unpleasant and unacceptable way. English = (be) uncouth.