It's misuse on FR, has totally left the term bereft of ANY meaning at all.
NoPardons is right, the term was invented by the conservatives of the late 1980s, themselves. But it is not true, IMO, that "neo-conservative" is now a hate term. It might be in the US, but in most of the English speaking world, it just means people who became conservative AFTER the rise of the New Right in the late 1970s. The "neo-con" agenda was supposed to be post-Cold War, more interested in maintaining Western supremacy, rather than kicking a dead horse by being anti-Soviet.