No, that's revolution. Literally, a return to the state of nature from which a new social contract can be drawn. If your revolution takes place in an orderly, legalistic fashion, leaving the old order diminished but still in place, you might call it secession. You might call it being granted independence. Seccession is a subset of Revolution.
Secession is: "I hate everything about you. I am leaving and unless you want to kill me over this, its over. your free to live your life how ever you want without me".
Revolutionary war is: "I hate everything about you and I am going to force us to live together but this time under MY rules. That is, if I don't decide to kill you"
My first reaction is that by that definition, the American Revolution is misnamed. My second is to wonder what the magic words are that turn my insurrection into a secession that, if I understand you correctly, the government has no moral authority to resist. If I say that I'm only claiming California, or Texas, or the entire south, does that mean by definition that I'm not rebelling?
I never mentioned "moral authority". I mentioned justification. Justification in the minds of the people about to carry out an action, that it is the right thing to do.
Perhaps it was misnamed.
"But what do we mean by the American Revolution? Do we mean the American war? The Revolution was effected before the war commenced. The Revolution was in the minds and hearts of the people; a change in their religious sentiments of their duties and obligations. ...This radical change in the principles, opinions, sentiments, and affections of the people, was the real American Revolution." -John Adams
Revolution is something that is happening right now, even as we type back and forth to each other. Its something that is happening at every "tea party" and every town hall meeting. It is something that happens in the minds and hearts of the people. That can either culminate in an attempt to secede peacefully or another American war. Either way, the revolution is already effected. Our argument, it seems, is over the method of finalization.