A passing track is a section of a railway system that allows trains to pass each other without causing any disruption to the schedule. However, there are different synonyms for the term "passing track" that vary slightly in their meaning and usage. Some alternatives include "siding," "loop," "overtaking track," "secondary track," and "runaround track." A siding typically refers to a short length of track leading off the main line, whereas a loop is a longer section of track that forms a loop. Overtaking track and secondary track are similar to passing tracks, but they often refer to tracks that are used less frequently. Runaround tracks, on the other hand, allow trains to reverse direction and change direction.