The Collaborative International Dictionary of English v.0.48:

Promiscuity \Pro`mis*cu"i*ty\, n.
   Promiscuousness; confusion. --H. Spencer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

promiscuity
    n 1: indulging in promiscuous (casual and indiscriminate) sexual
         relations [syn: promiscuity, promiscuousness, sleeping
         around]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "promiscuity":
   casualness, chambering, crudity of intellect, derangement,
   disarrangement, disarray, disarticulation, discomfiture,
   discomposure, disconcertedness, disharmony, dishevelment,
   disintegration, disjunction, disorder, disorderliness,
   disorganization, disproportion, disruption, disturbance,
   easy virtue, entropy, haphazardness, imprudence, incoherence,
   indiscreetness, indiscretion, indiscriminateness, indiscrimination,
   inharmonious harmony, insensibility, insensitivity, irregularity,
   lack of feeling, lack of refinement, laxity, lightness,
   loose morals, looseness, most admired disorder, nonsymmetry,
   nonuniformity, perturbation, promiscuousness, randomness,
   sleeping around, swinging, syncretism, tactlessness, turbulence,
   uncriticalness, undiscriminatingness, undiscriminativeness,
   unfastidiousness, unmeticulousness, unparticularness,
   unpreciseness, unselectiveness, unsymmetry, untactfulness,
   ununiformity, upset, wantonness, waywardness, whorishness