Don't be offended if by the original intent of the term you mean something like "classical liberal." Today's libertarians are, as you said, closer to anarchists than anything the Founding Fathers had in mind, just as today's liberals are closer to Stalin than the Founding Fathers, who were liberal in the classical sense.
These terms are usually referring to the contemporary definitions, unless they have been stipulated.
I do mean 'classic liberal' by that term. The word 'liberal' has been forfeited to the socialists, but while the word 'libertarian' is still in dispute I will continue to argue for its proper meaning.