As a Verb or Adjective: 1. To know someone or something because you have seen or heard them before or because someone has described them to you. English = recognise. Interactive: 1. Use alone to seek confirmation that your conversational partner knows who or what you are talking about. As Modifier: 1. Used to introduce a topic of conversation, just before you name the person or the thing, as in "You know John, well....", "You know that new smoking law, well...".