Sociosexual orientation (or sociosexuality) is the
individual difference in the willingness to engage in sexual activity
outside of a committed relationship. Individuals with a more restricted sociosexual orientation are less willing to engage in casual sex; they prefer greater love, commitment and emotional closeness before having sex with romantic partners. Individuals who have a more unrestricted sociosexual orientation are more willing to have casual sex and are more comfortable engaging in sex without love, commitment or closeness.
This is a rather new term I
think, 2014 being the first
time I have encountered it. Sociosexuality is a psychological or clinical term for promiscuity, or the degree of it, i.e. high or low.