unconstraint \un`constraint"\, n.
   freedom from constraint; ease. --felton.
   1913 webster

unconstraint
     n : the trait of lacking restraint or control; freedom from
         inhibition or worry; "she danced with abandon" syn: abandon,
          wantonness
see also:
abandon wantonness 

112 moby thesaurus words for "unconstraint":
   bohemianism, abandon, abandonment, accessibility, affability,
   approachability, artlessness, bluffness, bluntness, broadness,
   brusqueness, candidness, candor, casualness, common touch,
   communicativeness, conversableness, cordiality, crapulence,
   crapulency, crapulousness, directness, drunkenness, ease, easiness,
   easygoingness, excess, excessiveness, extravagance, extroversion,
   familiarity, folksiness, forthrightness, frankness, freedom,
   freeness, genuineness, gluttony, graciousness, homeliness,
   homeyness, immoderacy, immoderateness, immoderation, impulsiveness,
   incontinence, indiscipline, indulgence, informality, informalness,
   ingenuousness, inordinacy, inordinateness, instinctiveness,
   intemperance, intemperateness, irregularity, irrepressibility,
   laxness, licentiousness, looseness, naivete, naturalness,
   noncoercion, nonintimidation, offhandedness, openheartedness,
   openness, outgoingness, outspokenness, overdoing, overindulgence,
   permissiveness, plain dealing, plain speaking, plainness,
   plainspokenness, prodigality, relaxedness, riotousness, roundness,
   self-indulgence, simplicity, sincerity, sociability, spontaneity,
   straightforwardness, swinishness, talkativeness, too much,
   too-muchness, unaffectedness, unceremoniousness, unconstrainedness,
   uncontrol, unconventionality, uninhibitedness, unpretentiousness,
   unrepression, unreserve, unreservedness, unrestraint,
   unrestriction, unreticence, unruliness, unsecretiveness,
   unsophistication, unstrictness, unsuppression, untaciturnity,
   wantonness, wildness