The Collaborative International Dictionary of English v.0.48:

Suppressive \Sup*press"ive\, a.
   Tending to suppress; subduing; concealing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

suppressive
    adj 1: tending to suppress; "the government used suppressive
           measures to control the protest"

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "suppressive":
   absolute, absolutist, absolutistic, arbitrary, aristocratic,
   arrogant, authoritarian, authoritative, autocratic, bossy, choking,
   constraining, constrictive, contrary, counterproductive, crosswise,
   despotic, dictatorial, domineering, exclusive, feudal, forbidding,
   grinding, high-handed, hindering, hindersome, imperative, imperial,
   imperious, in the way, inhibiting, inhibitive, inhibitory,
   interdictive, interdictory, interrupting, interruptive, lordly,
   magisterial, magistral, masterful, monocratic, obstructing,
   obstructive, obstruent, occlusive, oppressive, overbearing,
   overruling, peremptory, preclusive, preventive, prohibiting,
   prohibitive, prohibitory, proscriptive, repressive, restraining,
   restrictive, severe, stifling, strangling, strict, stultifying,
   troublesome, tyrannical, tyrannous