1834, "indiscriminate mixture," from French promiscuité (1752), from Latin promiscuus "mixed" (see promiscuous) + French -ité (see -ity). Sexual sense is from 1844. Earlier was promiscuousness (by 1773 general; 1808 sexual).
Promethean
Prometheus
promethium
prominence
prominent
promiscuity
promiscuous
promise
promising
promisor
promissory