WordNet (r) 3.0 (2006):

mutant
    adj 1: tending to undergo or resulting from mutation; "a mutant
           gene"
    n 1: (biology) an organism that has characteristics resulting
         from chromosomal alteration [syn: mutant, mutation,
         variation, sport]
    2: an animal that has undergone mutation

The Free On-line Dictionary of Computing (19 January 2023):

mutant

    Microsoft's term for a mutex which is
   generally used in user mode but can also be used in kernel
   mode.  According to this terminology a mutex is only used in
   kernel mode.

   ["Microsoft Windows NT Workstation Resource Kit"].

   (1997-07-30)