That is the only useful definition of railroad in terms of D&D. It doesn't matter that you use a warped definition to avoid perceived negative connotations.
The problem is that people define "railroading" in so many different ways. I hate the term because of the negative implications. When I hear the word it makes me think "really bad DM who doesn't know how to run a game so forces the players to do things they don't want to so that he can make up for his lack of skill".
And I don't consider RPGA DMs or anyone who runs through a written adventure to be a bad DM. Nor do I view what they are doing as forcing anyone to do anything they don't want to.
The difference to me is the forcing part. When I sit down at an RPGA table, it's because I WANT to play the adventure. I've likely read the synopsis and know the basic outline of the plot and I want to play through it. When an NPC in the adventure comes up to me and asks me to find his family's ancient heirloom from their ancestral crypt, I know I'm going to say yes. Not because the DM is railroading me, but because I want to know what monsters are in the crypt, I want the challenge of defeating them, I want the reward that comes with succeeding.
I only feel railroaded when the DM actively says "No, you can't do that" or appears to be blatantly preventing me from taking an action. If I never come up against that barrier, then I don't care if I'm being "railroaded". Part of the unspoken agreement of playing through a written adventure of any sort is that the players won't actively attempt to break the adventure.
It's the "play through the story as written" that is objectionable to some people.
I guess. I figure I'm playing through the story as written no matter which game I'm playing in. Even in a purely home game, the DM has done some preparation(or at least I hope they have), they know what the enemies are likely to do, they've set up a plot hook, thought about the likely outcomes and courses of action that the PCs will take and written down details of what will happen in those circumstances. Either that or they are entirely winging it...and I don't like games run without preparation.
But if an NPC comes to me in a home game and asks me to find his heirloom in a home game, I should expect that the DM has a map of that crypt made up, a list of encounters and treasures found there and so on. If I say yes, I'm already agreeing to play the story as written, same as in the RPGA game. Only difference is, if I say no, I'm forcing the DM to write up an entirely new adventure in a home game.