The Jargon File (version 4.4.7, 29 Dec 2003):

zorkmid
 /zork'mid/, n.

    The canonical unit of currency in hacker-written games. This originated in
    Zork but has spread to nethack and is referred to in several other
    games.


The Free On-line Dictionary of Computing (30 December 2018):

zorkmid

    /zork'mid/ The canonical unit of currency in
   hacker-written games.  This originated in Zork but has
   spread to nethack and is referred to in several other games.

   [Jargon File]

   (1998-09-21)