A trope or tropus may refer to a variety of different concepts in medieval, 20th-, and 21st-century music. The term trope derives from the Greek τρόπος (tropos), "a turn, a change", related to the root of the verb τρέπειν (trepein), "to turn, to direct, to alter, to change".. The Latinised form of the word is tropus. In music, a trope is adding another section, or trope to a plainchant or section of plainchant, thus making it appropriate to a particular occasion or festival.