The Collaborative International Dictionary of English v.0.48:

Preclusive \Pre*clu"sive\, a.
   Shutting out; precluding, or tending to preclude; hindering.
   -- Pre*clu"sive*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

preclusive
    adj 1: made impossible [syn: preclusive, obviating(a)]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "preclusive":
   deterrent, deterring, discouraging, ethnocentric, exceptional,
   excluding, exclusive, exclusory, forbidding, forestalling,
   inadmissible, inhibitive, inhibitory, insular, interdictive,
   interdictory, narrow, parochial, prescriptive, preventative,
   preventive, prohibiting, prohibitive, prohibitory, prophylactic,
   proscriptive, repressive, restrictive, seclusive, segregative,
   select, selective, separative, snobbish, suppressive, xenophobic