The Collaborative International Dictionary of English v.0.48:

Undisciplined \Undisciplined\
   See disciplined.

WordNet (r) 3.0 (2006):

undisciplined
    adj 1: not subjected to discipline; "undisciplined talent"
    2: not subjected to correction or discipline; "let her children
       grow up uncorrected" [syn: uncorrected, undisciplined]
    3: lacking in discipline or control; "undisciplined behavior";
       "ungoverned youth" [syn: undisciplined, ungoverned]

Moby Thesaurus II by Grady Ward, 1.0:

138 Moby Thesaurus words for "undisciplined":
   adrift, afloat, alternating, amorphous, bad, bibulous, capricious,
   changeable, changeful, crapulent, crapulous, desultory, deviable,
   disobedient, dizzy, eccentric, erratic, excessive, extravagant,
   extreme, fast and loose, fickle, fitful, flickering, flighty,
   flitting, fluctuating, fractious, freakish, froward, giddy,
   gluttonous, headstrong, heady, immoderate, impetuous, impulsive,
   inconsistent, inconstant, incontinent, indecisive, indisciplined,
   indulgent, infirm, inordinate, insubordinate, intemperate,
   intractable, irregular, irresolute, irresponsible, lawless,
   licentious, mazy, mercurial, moody, mutinous, naughty,
   nonconforming, obstinate, overindulgent, overindulging, prodigal,
   rambling, rampant, recalcitrant, recusant, reinless, restless,
   roving, scatterbrained, self-indulgent, self-willed, shapeless,
   shifting, shifty, shuffling, spasmodic, spineless, swinish,
   too much, transgressive, unaccountable, unbridled, uncertain,
   unchecked, uncomplying, unconstrained, uncontrollable,
   uncontrolled, uncurbed, undependable, unduteous, undutiful,
   uneducated, unfixed, unfrugal, ungovernable, ungoverned, unlimited,
   unmanageable, unmeasured, unpredictable, unprepared, unreined,
   unreliable, unrestrained, unruly, unschooled, unsettled, unstable,
   unstable as water, unstaid, unsteadfast, unsteady, untaught,
   unthrifty, untoward, untrained, untutored, vacillating, vagrant,
   variable, vicissitudinary, vicissitudinous, violative, volatile,
   wandering, wanton, wavering, wavery, wavy, wayward, whimsical,
   wild, wildcat, willful, wishy-washy