Broadly-used term for linear plotting in RP Gs. (1) GM behavior when the planned scenario requires a particular sequence of events/scenes leading to a particular ending. The GM ensures that it arrives there by a variety of means. This is generally pejorative, but is sometimes defended as valid as long as it is not overused. (2) On the Forge, a purely negative term for GM behavior that breaks the Social Contract via the GM controlling a player-character's decisions or opportunities for decisions.

References:

• So... What is Railroading? (Using Illusionism Terminology)
• Railroading, Star Wars, and more
• Railroading Fun