Word parts incest + -ous Pronunciation (UK) IPA (key): /ɪnˈsɛstjuəs/ or /ɪnˈsɛst͡ʃuəs/ (US) IPA (key): /ɪnˈsɛst͡ʃuəs/ Audio (UK)(file) Adjective Positive incestuous Comparative more incestuous Superlative most incestuous An act that is incestuous is an act of incest. A person who is incestuous is someone who participates in incest. Having sex with your sister is incestuous. Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads