1.
side road, side street, byway
A smaller road branching off from the main road.
2.
digression, tangent, sidetrack
A departure from the main topic or the primary course of action. Often used with にそれる to describe straying off topic.
Usage
The figurative sense (digression) is very common. The key pattern is 脇道にそれる (to stray off onto a side road / to digress). This expression works both literally (taking a physical detour) and figuratively (going off topic).
Common collocations
Related Words
Related:
裏通り (back street, side street)