Short answers, pulled from the story.
A literary trope is an artistic effect realized through figurative language, such as a word, phrase, or image used in a non-literal way. The word derives from the Greek for "a turn" or "a change", related to a verb meaning "to turn, to direct, to alter".
Kenneth Burke identified metaphor, metonymy, synecdoche, and irony as the "four master tropes" because of their high frequency in everyday discourse. He grouped them together to highlight how these figures structure ordinary language, not just poetry or formal rhetoric.
In medieval practice, tropes were amplifications added to fixed liturgical texts such as the Kyrie Eleison. The most significant example is the Quem quaeritis?, placed before the Easter Sunday Introit and recognized as the source of liturgical drama. This practice ended when Pope Pius V promulgated the Tridentine Mass in 1570.
In its original rhetorical sense, a trope is any figurative substitution of a less literal word or phrase for a literal one. Semantic change has broadened the term so it also covers commonly recurring or overused techniques, motifs, and clichés in creative literature.
Tropological criticism is the historical study of tropes that aims to define the dominant tropes of a given epoch and to locate them in both literary and non-literary texts. Michel Foucault is named as an important exemplar of this interdisciplinary approach.
Metonymy substitutes one thing for another through proximity or correspondence, such as calling presidential actions "actions of the White House". Synecdoche is a related device that substitutes a part for a whole, a whole for a part, or a specific for a general, such as calling workers "hired hands".