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]