The Macmillan English dictionary for Advanced Learners defines snob as ‘someone who thinks and behaves as if they are better than other people, usually because of their social class’. If you call someone a snob, this usually means that you don’t like their superior attitude and behaviour.
Some people have argued that the word derives from an abbreviated form of the Latin 'sine nobilitate', meaning 'without nobility', in other words a 'common' person. Others suggest that a snob was originally a shoemaker (a very humble profession in years gone by) and that it was used in the 18th century by the highly privileged upper-class students of Cambridge University to describe anyone who was of humble origin or an 'inferior' class. Gradually the word began to be applied to social climbers who aped the manners and behaviour of the upper classes and finally to anyone behaving in a superior manner. Related words are the adjective snobbish and the noun snobbery.