from
The Collaborative International Dictionary of English v.0.48
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.
[Webster 1913 Suppl.]
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.
[Webster 1913 Suppl.]