Source : Webster's Revised Unabridged Dictionary (1913)

Sidetrack \Side"track`\, v. t. [imp. & p. p. {Sidetracked}; p.
   pr. & vb. n. {Sidetracking}.]
   1. (Railroads) To transfer to a siding from a main line of
      track.

   2. Hence, fig., to divert or reduce to a position or
      condition that is relatively secondary or subordinate in
      activity, importance, effectiveness, or the like; to
      switch off; to turn aside, as from a purpose. [Colloq.]

            Such a project was, in fact, sidetracked in favor of
            the census of school children.        --Pop. Sci.
                                                  Monthly.

Source : WordNet®

sidetrack
     n : a short stretch of railroad track used to store rolling
         stock or enable trains on the same line to pass [syn: {siding},
          {railroad siding}, {turnout}]
     v : wander from a direct or straight course [syn: {depart}, {digress},
          {straggle}]