The Collaborative International Dictionary of English v.0.48:

Abut \A*but"\, v. i. [imp. & p. p. Abutted; p. pr. & vb. n.
   Abutting.] [OF. abouter, aboter; cf. F. aboutir, and also
   abuter; a (L. ad) + OF. boter, buter, to push: cf. F. bout
   end, and but end, purpose.]
   To project; to terminate or border; to be contiguous; to
   meet; -- with on, upon, or against; as, his land abuts on the
   road.
   [1913 Webster]

WordNet (r) 3.0 (2006):

abut
    v 1: lie adjacent to another or share a boundary; "Canada
         adjoins the U.S."; "England marches with Scotland" [syn:
         border, adjoin, edge, abut, march, butt, butt
         against, butt on]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "abut":
   abut on, adjoin, appose, be based on, be contiguous, be in contact,
   bear on, bestraddle, bestride, border, border on, bring near, butt,
   communicate, conjoin, connect, join, juxtapose, juxtaposit,
   lean on, lie by, lie on, line, march, neighbor, perch, put with,
   rely on, repose on, rest on, ride, sit on, stand by, stand on,
   straddle, stride, touch, verge, verge upon