The Collaborative International Dictionary of English v.0.48:

Insubordinate \In`sub*or"di*nate\, a.
   Not submitting to authority; disobedient; rebellious;
   mutinous.
   [1913 Webster]

WordNet (r) 3.0 (2006):

insubordinate
    adj 1: not submissive to authority; "a history of insubordinate
           behavior"; "insubordinate boys" [ant: subordinate]
    2: disposed to or engaged in defiance of established authority
       [syn: insubordinate, resistant, resistive]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "insubordinate":
   agitator, brawler, contrary, contumacious, defiant, disaffected,
   disobedient, dissentious, extremist, factious, fractious, frondeur,
   headstrong, heady, incompliant, indocile, insurgent,
   insurrectional, insurrectionary, insurrectionist, insurrecto,
   intractable, irresponsible, lawless, licentious, malcontent,
   maverick, mutineer, mutinous, nonconformist, noncooperating,
   noncooperative, obstreperous, perverse, rampant, rebel, rebellious,
   recalcitrant, refractory, reinless, revolter, revolutionary,
   revolutionist, rioter, seditious, self-willed, subversive, traitor,
   unaccountable, unbridled, unchecked, uncompliant, uncomplying,
   uncontrolled, uncooperative, uncurbed, undisciplined, ungovernable,
   ungoverned, unreined, unrestrained, unruly, unsubmissive, wildcat,
   willful