The Collaborative International Dictionary of English v.0.48:

Unsubmissive \Unsubmissive\
   See submissive.

WordNet (r) 3.0 (2006):

unsubmissive
    adj 1: not servile or submissive [syn: unservile,
           unsubmissive] [ant: servile]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "unsubmissive":
   beyond control, breachy, complaining, contrary, contumacious,
   defiant, deviant, disputatious, disputing, dissentient, dissenting,
   dissident, fractious, incorrigible, indocile, indomitable,
   insubordinate, insuppressible, intractable, irrepressible,
   nonconformable, nonconforming, noncooperating, noncooperative,
   nonobservant, objecting, obstreperous, obstructive,
   on the barricades, out of hand, proof against, protesting,
   rebellious, recalcitrant, recusant, refractory, reluctant,
   renitent, repellent, resistant, resisting, resistive, restive,
   retardant, retardative, shrewish, unadaptable, unadjustable,
   unbiddable, uncompliant, unconforming, uncontrollable,
   uncooperative, ungovernable, unmalleable, unmanageable, unmoldable,
   unruly, unyielding, up in arms, wild, withstanding