The Collaborative International Dictionary of English v.0.48:

Disqualification \Dis*qual`i*fi*ca"tion\, n.
   1. The act of disqualifying, or state of being disqualified;
      want of qualification; incompetency; disability; as, the
      disqualification of men for holding certain offices.
      [1913 Webster]

   2. That which disqualifies; that which incapacitates or makes
      unfit; as, conviction of crime is a disqualification of a
      person for office; sickness is a disqualification for
      labor.
      [1913 Webster]

            I must still retain the consciousness of those
            disqualifications which you have been pleased to
            overlook.                             --Sir J.
                                                  Shore.
      [1913 Webster]

WordNet (r) 3.0 (2006):

disqualification
    n 1: unfitness that bars you from participation
    2: the act of preventing someone from participating by finding
       them unqualified

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "disqualification":
   ad lib, disability, disablement, extemporaneousness, imbecility,
   improvisation, inability, inadequacy, incapability, incapacitation,
   incapacity, incompetence, incompetency, inefficiency, ineptitude,
   infancy, inferiority, insufficiency, lack of preparation,
   legal incapacity, minority, nonpreparation, nonpreparedness,
   planlessness, unfitness, unfittedness, unpreparedness,
   unqualification, unqualifiedness, unreadiness, unsuitability,
   unsuitableness, unsuitedness, vulnerability, wardship