Digress
Part of speech: verb
Definition: To step or turn aside; to deviate; to swerve; especially, to turn aside from the main subject of attention, or course of argument, in writing or speaking. To turn aside from the right path; to transgress; to offend.
Sidetrack
Part of speech: verb
Definition: To divert (a locomotive) on to a lesser used track in order to allow other trains to pass.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.To sideline; to push aside; to divert or distract from, reducing (something) to a secondary or subordinate position.To deviate briefly from the topic at hand.
Part of speech: noun
Definition: 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.(sometimes) Any auxiliary railroad track, as differentiated from a siding, that runs adjacent to the main track.A smaller tunnel or well drilled as an auxiliary off a main tunnel or well.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.