Tony Woodlief's definition:
A real American conservative, to me, is someone who understands that markets are the best means of allocating resources, that liberty is essential to human thriving, and that man is sinful and in desperate need of checking and elevating institutions like the Church and marriage and childrearing. A real American conservative believes in aspiring, at the very least, to truthfulness and humility and thoughtfulness, which means he can’t help but cringe when he hears the likes of an Ann Coulter bellowing about her enemies being traitors. A real American conservative understands that the ills of mankind will not go away if we could only just have a lower tax rate and less regulation.
A real American conservative is not, I’ll submit to you, at home in the maneuvering and manipulation of state capitols, and certainly not in Washington, D.C. A real American conservative does not trust large government or mass democracy or even himself, certainly not himself, which is why he wants to keep undivided power out of any man’s hands, including his own.
I don't disagree with much of that. And if you want to read a modern philosophical defense of it, try this.