The Collaborative International Dictionary of English v.0.48:

Byway \By"way`\, n.
   A secluded, private, or obscure way; a path or road aside
   from the main one. " Take no byways." --Herbert.
   [1913 Webster]

WordNet (r) 3.0 (2006):

byway
    n 1: a side road little traveled (as in the countryside) [syn:
         byway, bypath, byroad]

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "byway":
   Autobahn, US highway, alley, alleyway, arterial, arterial highway,
   arterial street, artery, autoroute, autostrada, avenue, back door,
   back road, back stairs, back street, back way, belt highway,
   blind alley, boulevard, by-lane, bypass, bypath, byroad, bystreet,
   camino real, carriageway, causeway, causey, chaussee,
   circumferential, close, corduroy road, county road, court,
   crescent, cul-de-sac, dead-end street, departure, detour,
   deviation, digression, dike, dirt road, discursion, drive,
   driveway, episode, excursion, excursus, expressway, freeway,
   gravel road, highroad, highway, highways and byways,
   interstate highway, lane, local road, main drag, main road, mews,
   motorway, parkway, pave, paved road, pike, place, plank road,
   primary highway, private road, right-of-way, ring road, road,
   roadbed, roadway, roundabout way, route nationale, row, royal road,
   secondary road, side door, side path, side road, side street,
   sidetrack, speedway, state highway, street, superhighway, terrace,
   thoroughfare, through street, thruway, toll road, township road,
   turnpike, wynd