Another five common railroading terms:

Interlocking (Int)
A predetermined sequence of signals and signal appliances to ensure that movements must succeed each other in the correct order. This is to prevent signals being displayed simultaneously on conflicting routes.

Interlocking Appliances
Are parts of any interlocking capable of movement like: switches, movable point frogs, derails, locks, movable bridges etc.

Interlocking Limits
The trackage between the opposing home signals of an interlocking.

Interlocking Signals
The fixed signals of an interlocking.

Interlocking Station
The location from where an interlocking is operated.

Happy Railroading!