The Collaborative International Dictionary of English v.0.48:

outspan \out*span"\, v. t. & i. [D. uitspannen.]
   To unyoke or disengage, as oxen from a wagon; to unharness (a
   horse). [S. Africa]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

outspan \out"span\, n.
   1. The act of outspanning.
      [PJC]

   2. A place where outspanning is done; Hence: An encampment.
      [South African]
      [PJC]

WordNet (r) 3.0 (2006):

outspan
    v 1: remove the yoke or harness from; "outspan the draft
         animals" [ant: inspan]