n. a railroad system where the trains run on one rail
n. a train running on a single rail
The Century Dictionary and Cyclopedia
n. A railway in which the cars run on a single rail.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a railway having a single track
Word Usage
"There weren't many people (the monorail is also unheated for the most part), so the conductor/volunteer (Dave -- Mason read his name badge, the budding secret agent that he is,) let us sit at the front by the driver's seat."