Source : Webster's Revised Unabridged Dictionary (1913)

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

Source : WordNet®

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