The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Thesis: A term with several distinct meanings but perhaps most commonly used in universities to refer to a paper or monograph written by a degree-seeking candidate in fulfillment of academic requirements or to the position taken by someone expostulating on a particular topic with the intent of proving a position. The term is sometimes also equated with theme, particularly the main idea advanced by an author in a text. In prosody (the study of versification), there are two uses of thesis: the original Greek usage, in which thesis refers to a stressed syllable in a foot of verse (as opposed to the arsis, or unstressed syllable); and the later Latin usage, in which the terms were reversed, with thesis referring to an unstressed syllable (and arsis to a stressed one). Thus, according to Greek usage, the thesis of the word thesis falls on the first (the stressed) syllable, whereas under the Latin usage, the thesis of the word thesis falls on the second (the unstressed) syllable.