The Collaborative International Dictionary of English v.0.48:

Highway \High"way`\, n.
   A road or way open to the use of the public, especially a
   paved main road or thoroughfare between towns; in the latter
   sense it contrasts with local street; as, on the highways
   and byways.

   Syn: Way; road; path; course.
        [1913 Webster]

WordNet (r) 3.0 (2006):

highway
    n 1: a major road for any form of motor transport [syn:
         highway, main road]