The Collaborative International Dictionary of English v.0.48:

Uncurbed \Uncurbed\
   See curbed.

WordNet (r) 3.0 (2006):

uncurbed
    adj 1: not restrained or controlled; "unbridled rage"; "an
           unchecked temper"; "ungoverned rage" [syn: unbridled,
           unchecked, uncurbed, ungoverned]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "uncurbed":
   abandoned, disobedient, go-go, headstrong, heady, immoderate,
   incontinent, indulgent, insubordinate, intemperate, irrepressible,
   irresponsible, lawless, lax, licentious, loose, mutinous,
   nonrestrictive, out of control, out of hand, permissive, rampant,
   reinless, riotous, self-willed, unaccountable, unbridled,
   unchecked, uncoerced, uncompelled, unconstrained, uncontrolled,
   undisciplined, unforced, ungoverned, unhampered, uninhibited,
   unmastered, unmeasured, unmuzzled, unreined, unrepressed,
   unreserved, unrestrained, unrestrictive, unruly, unsubdued,
   unsuppressed, untrammeled, wanton, wild, wildcat, willful,
   withdrawn