fornicate

v [I] (fml esp derog 文, 尤作贬义) (of people not married to each other) have sexual intercourse （指无婚姻关系的人之间）性交; 通奸.

formality, formalization, formalisation, formalize, formalise, formally, format, formation, formative, formed, former, formerly, formic acid, Formica, formidable, formidably, formless, formlessly, formula, formulaic, formulate, formulation, fornication, forsake, forsaken, forseeable, forswear, forsythia, fort, forte, forth, forthcoming, forthright, forthwith, fortieth, fortification, fortified wine, fortify, fortissimo, fortitude, fortnight, fortnightly,