The Collaborative International Dictionary of English v.0.48:

Laxity \Lax"i*ty\ (l[a^]ks"[i^]*t[y^]), n. [L. laxitas, fr.
   laxus loose, slack: cf. F. laxit['e], See Lax, a.]
   The state or quality of being lax; lack of tenseness,
   strictness, or exactness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

laxity
    n 1: the condition of being physiologically lax; "baths can help
         the laxness of the bowels" [syn: laxness, laxity]
    2: the quality of being lax and neglectful [syn: laxness,
       laxity, remissness, slackness]

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "laxity":
   allowance, amorphousness, approximation, bagginess, blobbiness,
   blurriness, broadness, carelessness, chambering, culpa,
   culpable negligence, default, delinquency, dereliction, deviation,
   disconformity, disorder, disregard, easiness, easy virtue,
   easygoingness, failure, flabbiness, flaccidity, flaccidness,
   floppiness, fogginess, fuzziness, generality, haziness,
   ill-definedness, impotence, imprecision, inaccuracy,
   inaccurateness, inadvertence, inadvertency, inattention,
   inchoateness, incoherence, incorrectness, indecisiveness,
   indefinableness, indefiniteness, indeterminateness, indifference,
   indistinctness, inexactitude, inexactness, inobservance, laches,
   laissez-faire, lapse, laxation, laxness, leniency, lightness,
   limpness, loose morals, looseness, loosening, mistiness, neglect,
   neglectfulness, negligence, nonadherence, noncompliance,
   nonconformance, nonconformity, nonfeasance, nonfulfillment,
   noninterference, nonobservance, nonperformance, nonrestriction,
   obscuration, obscurity, omission, overindulgence, overlooking,
   overpermissiveness, oversight, permissiveness, poor stewardship,
   predictable error, probable error, procrastination, promiscuity,
   relaxation, relaxedness, remissness, ricketiness, rubberiness,
   shakiness, shapelessness, slackness, sleeping around, slight,
   sloppiness, softness, standard deviation, sweepingness, swinging,
   tolerance, unclearness, uncorrectness, unfactualness, unobservance,
   unpreciseness, unrestraint, unrigorousness, vagueness, wantonness,
   waywardness, weakness, whorishness