The Collaborative International Dictionary of English v.0.48:

Chasmy \Chas"my\ (k[a^]z"m[y^]), a.
   Of or pertaining to a chasm; abounding in chasms. --Carlyle.
   [1913 Webster]

         They cross the chasmy torrent's foam-lit bed.
                                                  --Wordsworth.
   [1913 Webster]