Mississippi Code
In General
§ 97-29-1. Adultery and fornication; unlawful cohabitation

If any man and woman shall unlawfully cohabit, whether in adultery or fornication, they shall be fined in any sum not more than five hundred dollars each, and imprisoned in the county jail not more than six months; and it shall not be necessary, to constitute the offense, that the parties shall dwell together publicly as husband and wife, but it may be proved by circumstances which show habitual sexual intercourse.