Source : Webster's Revised Unabridged Dictionary (1913)

Endlong \End"long`\ (?; 115), adv. & prep. [Cf. {Along}.]
   Lengthwise; along. [Archaic]

         The doors were all of adamants eterne, I-clenched
         overthwart and endelong With iron tough. --Chaucer.

         He pricketh endelong the large space.    --Chaucer.

         To thrust the raft endlong across the moat. --Sir W.
                                                  Scott.