The most highly approved of DMs do tend to be good at concealing the railroad tracks...

I was trying to scroll through https://en.wikipedia.org/wiki/DM but couldn't find anything fitting... Am I too old or two young or too out of touch? :D

I think they mean Dungeon Master, the architect / narrator of multiplayer role playing games. A good DM will guide the players through a well-planned story, in part by making the layers feel that they are in control of the story themselves.

I'm not into gaming so didn't make the connection. Thanks!

This exactly.