Entry 1 sense Webster, 1913 Marchioness /mär'-shən-ĭs/ · Mar·chion·ess · IPA /ˈmɑɹʃənɪs/ 01 n. The wife or the widow of a marquis; a woman who has the rank and dignity of a marquis. 1. The wife or the widow of a marquis; a woman who has the rank and dignity of a marquis.