- (of a railroad or section of a railroad's route) having but one set of tracks, so that trains going in opposite directions must be scheduled to meet only at points where there are sidings.
- having a narrow scope; one-track: He has a single-track mind.
- an off-road trail used by cyclists, wide enough for only one bicycle at a time
- (of a railway) having only a single pair of lines, so that trains can travel in only one direction at a time
- (of a road) only wide enough for one vehicle
- able to think about only one thing; one-track
