A neocon is someone who agrees politically with conservative ideas including free market capitalism. Moderate conservatives tend to clash with neocons on issues of foreign policy.
Faith in the free market is one important belief of neocons, but even more important is their support of interventionism. In other words, neocons support actively promoting democracy around the world, even if that means using military force. Neocon is short for neoconservative, which adds the neo-, or "new," prefix to conservative. The original neocons abandoned their formerly leftist ideals in the late 1960s and early 1970s.