As a Noun: 1. Behaviour which is rude or disrespectful, especially used of children towards adults. Informal English = cheek, rudeness. English = impertinence, impudence, insolence. As a Verb or Adjective: 1. To behave in a rude or disrespectful way, especially children to adults. Informal English = (be) cheeky, (be) rude. English = (be) impertinent, (be) impudent, (be) insolent. Idiomatic English = give cheek.