Re: Kafir
Literally, the word kaafir means 'someone who covers something up'. So by that, a person who covers his car at night with one of those protective sheets is a 'kaafir'.
Islamically, the word means 'the one who denies something despite having the knowledge'. So a Muslim who knows about his religion, but still does not believe, would be a 'kaafir', while someone who is a polytheist but was never introduced to Islam, is not a 'kaafir'.