1. Unlawful sexual intercourse on the part of an unmarried person; the act of such illicit sexual intercourse between a man and a woman as does not by law amount to adultery.
in England, the offense, though cognizable in the ecclesiastical courts, was not at common law subject to secular prosecution. In the united states it is indictable in some states at common law, in others only by statute.
2. Adultery. Incest.
Origin: f. Fornication, L. Fornicatio.