In"cest (?), n. [F. inceste, L. incestum unchastity, incest, fr. incestus unchaste; pref. in- not + castus chaste. See Chaste.]
The crime of cohabitation or sexual commerce between persons related within the degrees wherein marriage is prohibited by law.
Shak.
Spiritual incest. Eccl.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.
© Webster 1913.