term:

Fornication

fornication n

[Late Latin fornicatio, from fornicare to have intercourse with prostitutes, from Latin fornic- fornix arch, vault, brothel]
: consensual sexual intercourse between a man and esp. single woman who are not married to each other
;also
: the crime of engaging in fornication compare adultery NOTE: Where still considered a crime, fornication is classified as a misdemeanor.

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.