twincest

== English == === Etymology === Blend of twin +‎ incest or twin +‎ -cest. === Pronunciation === IPA(key): /ˈtwɪnsɛst/ Rhymes: -ɪnsɛst === Noun === twincest (uncountable) (chiefly fandom slang) Incestuous sexual relations between twins, or siblings who look very similar.