Used attributively before a noun, chiefly in historical or legal contexts (e.g., "paramour rights").
adultérinSens littéraire : relatif à une liaison illégitime ou à un amour interdit. The baron claimed paramour rights over his serfs.
Le baron revendiquait des droits adultérins sur ses serfs.
Archaic/obsolete adverbial use surviving in older literature meaning ‘with love; passionately’
Sir Lancelot served his lady paramour in every deed of arms.
Sir Lancelot servait sa dame amoureusement dans chaque geste d’armes.