What is a pundit?

A pundit is a person who has (or says he has) a great amount of knowledge in a particular area and who offers up his opinions in the mass media. Political pundits (whether actual or just self-proclaimed authorities of politics) show up a lot during presidential election years, but sports, entertainment, and fashion pundits are around all the time.
Pundit can have both a positive and a negative connotation. A pundit who you believe has actual authoritative knowledge is also referred to as a guru. The word pundit takes on a negative connotation when it's used to refer to someone who offers up biased information while pretending to be neutral. In the world of American politics, the opposite ends of pundits' biases are well-represented by Rush Limbaugh and Michael Moore.