The term is not always used the same way : some use it to refer to any extramarital sex outside of marriage , some use it to refer to sex in a casual relationship , and others use the word for one-time encounters , promiscuity , or to refer to sex in the absence of emotional attachment or love . The term is not always used consistently : some use it to refer to any extramarital sex , some use it to refer to sex in a casual relationship , whereas others reserve its use for one-time encounters , promiscuity , or to refer to sex in the absence of emotional attachment or love .