sidetrack

noun

1. A second, relatively short length of track just to the side of a railroad track, joined to the main track by switches at one or both ends, used either for unloading freight, or to allow two trains on a same track to meet (opposite directions) or pass (same direction); a railroad siding.
2. (sometimes)Any auxiliary railroad track, as differentiated from a siding, that runs adjacent to the main track.
3. A smaller tunnel or well drilled as an auxiliary off a main tunnel or well.
4. An alternate train of thought, issue, topic, or activity, that is a deviation or distraction from the topic at hand or central activity, and secondary or subordinate in importance or effectiveness.

   “Stay focused on the story; you keep getting lost in all of these little sidetracks.”

   “"However, I am down a side-track. What I wanted to say to you is that you must not take Bolsover's little spirit circus too seriously."”

verb

1. To divert (a locomotive or train) on to a lesser used track in order to allow other trains to pass.

   “It was just after 5 p.m.; would the non-stop "Capitals Limited" come up next? It was due in at 5.30 and other trains are often side-tracked in its favour.”

   “Two westbound freights were in the vicinity and the operator was kept busy passing them radio messages with the latest information on the late running of the streamliners, to allow the enginemen to keep moving until the last possible minute before they had to sidetrack their trains to let the fast trains overtake.”

2. To divert or distract (someone) from a main issue or course of action with an alternate or less relevant topic or activity; or, to use deliberate trickery or sly wordplay when talking to (a person) in order to avoid discussion of a subject.

   “Sorry I'm late. I got sidetracked helping my friend move some furniture.”

   “The politician sidetracked the reporter with a story about duck hunting instead of a direct response to the question that was asked.”

   “I hope you can sidetrack the teacher with questions so we don't have to take the exam.”

3. To sideline; to push aside; to divert or distract from, reducing (something) to a secondary or subordinate position.

   “The project was sidetracked in favor of a more popular program.”

   “He has sidetracked this debate for far too long.”

4. (intransitive)To deviate briefly from the topic at hand.

   “Just to sidetrack a little bit from the subject I will explain my reasoning.”

   “To sidetrack for a moment, let me commend this team for their outstanding efforts.”