Completely meaningless term when both Noam chomsky and the Koch brothers consider themselves libertarians.....%99 of the time though it refers to just another hydrahead of the ultra far right anarcho capitalists who want to privatize the police (after all, the poor don't have anything worth stealing)..and multi million dollar think tanks like the cato institute that tries to then pass it's self off as the voice of the average man.....Generally people who tend to think of John Stossel and Pen & Teller as being smarter than Gore Vidal which in turn makes me generally want to see them plowed over with steam rolls and their remains scooped up and sold off to mexican rendering plants.