(n.) A private lane, or one opening out of the usual road.

French door afterpart afterpiece archway back back road back seat back side back stairs back street back way backstairs barway behind bolt-hole breech bulkhead by-lane bypass bypath byroad bystreet byway carriage entrance cellar door cellarway clandestine covert covert way detour door doorjamb doorpost doorway escalier derobe escape hatch escape route feline front door furtive gate gatepost gateway hatch hatchway heel hidlings hind end hind part hindhead hole-and-corner hugger-mugger lintel occiput porch portal porte cochere posterior postern privy propylaeum pylon quiet rear rear end rearward reverse roundabout way scuttle secret exit secret passage secret staircase shifty side door side road side street skulking slinking slinky sly sneaking sneaky stealthy stern stile storm door surreptitious tail tail end tailpiece threshold tollgate trap trap door turnpike turnstile under-the-counter under-the-table undercover underground underground railroad underground route underhand underhanded unobtrusive