fornication

Etymology

From Middle English fornicacioun, from Old French fornicacion, from Latin fornicātiō, from fornix (“brothel”).

noun

1. (religion, law) Sexual intercourse by people who are not married to each other, or which is considered illicit in another way.
   Draw not near unto fornication; for it is wickedness, and an evil way 1734, George Sale, transl., Alcoran of Mohammed, 17:32
   In one case, where a man was sued for committing fornication with his wife before marriage, it appeared, that seven years after her death he was cited to stand as a prisoner at their bar, though he had lived with her for nine years,[…] 1816, Cobbett's Parliamentary History of England: From the Norman Conquest, in 1066, to the Year, 1803, page 623
   ... that he was a married man at the time is a necessary allegation, as the allegation that he was an unmarried man would have been necessary had he been charged with the crime of incest, by having committed fornication with his daughter. 1893, The Southwestern Reporter, page 840
   Thus, at Roxbury, 1678, Hanna Hopkins was censured in the church for fornication with her husband before marriage and for fleeing from justice into Rhode Island. 2013, Arthur W. Calhoun, The American Family in the Colonial Period, Courier Corporation
2. (colloquial) Sexual intercourse in general; sex.
   For a moment he stared at the back of the Lascar, wondering if he were the youth that he had disturbed during fornication with his Engineer, then dismissed all thoughts of the previous night, he was getting old, and suspicious, what did it matter […] 2012, Geoffrey Kennell, The Upper Crust, Xlibris Corporation, page 185