Origin: 1545–55; < Late Latin fornicātus (past participle of fornicārī to consort with prostitutes), equivalent to Latin fornic- (stem of fornix) arch, vault, basement, brothel + -ātus-ate1
1550s, from L.L. fornicatus, pp. of fornicari (see fornication). Or perhaps in some cases a back formation from fornication. Related: Fornicated; fornicating.