c. 1600, of people or things, "mingled confusedly or indiscriminately, consisting of parts or individuals grouped together without order, consisting of a disorderly mix," from Latin promiscuus "mixed, indiscriminate, in common, without distinction, to which all are admitted without distinction," from pro (see pro-) + miscere "to mix" (from PIE root *meik- "to mix").
Meaning "indiscriminate in sexual relations" is recorded by 1857, from promiscuity in the related sense, the meaning then shading into "not restricted to one individual." The Latin adjective also was used sexually, with conubia (of sexual union between patricians and plebeians). Related: Promiscuously; promiscuousness.
updated on December 06, 2020