incest /ˈɪn.sɛst/noun 2verb 1forms 3 noun2 •Sexual relations between close relatives, especially immediate family members and sometimes first cousins, usually considered taboo.Genetic problems caused by incest are thought to have plagued many royal families in the Middle Ages. •Romantic relationships between close relatives, also widely taboo. verb1 •To engage in incestuous sexual activities.I do not want anyone to feel that my lesbianism is a result of being incested. — 1994 formsincested · incesting · incests