n. In rhetoric, a figurative use of a word; a word or expression used in a different sense from that which properly belongs to it, or a word changed from its original signification to another for the sake of giving spirit or emphasis to an idea, as when we call a stupid fellow an ass, or a shrewd man a fox.n. In Gregorian music, a short cadence or closing formula by which particular melodies are distinguished. Also called differentia and distinctio.n. In liturgics, a phrase, sentence, or verse occasionally accompanying or interpolated in the introit, Kyrie, Gloria in Excelsis, Sanctus, and Agnus Dei in different parts of the Western Church. Since the sixteenth century tropes have no longer been used.n. A geometrical singularity, the reciprocal of a node.