Incest
Incest , noun
[French inceste, Latin incestum unchastity, incest, from incestus unchaste; pref. in- not + castus chaste. See Chaste.]
The crime of cohabitation or sexual intercourse between persons related within the degrees wherein marriage is prohibited by law;
sexual relations between closely related persons, usually taken as first cousins or closer. — Shakespeare
Collocations (1)
Spiritual incest (Ecclesiastical Law) , (a) The crime of cohabitation committed between persons who have a spiritual alliance by means of baptism or confirmation. (b) The act of a vicar, or other beneficiary, who holds two benefices, the one depending on the collation of the other.