Thesis The"sis, n.; pl. Theses. [L., fr. Gr. ?, fr. ? to place, set. See Do, and cf. Anathema, Apothecary, Epithet, Hypothesis, Parenthesis, Theme, Tick a cover.] 1. A position or proposition which a person advances and offers to maintain, or which is actually maintained by argument. 2. Hence, an essay or dissertation written upon specific or definite theme; especially, an essay presented by a candidate for a diploma or degree. I told them of the grave, becoming, and sublime deportment they should assume upon this mystical occasion, and read them two homilies and a thesis of my own composing, to prepare them. --Goldsmith. 3. (Logic) An affirmation, or distinction from a supposition or hypothesis. 4. (Mus.) The accented part of the measure, expressed by the downward beat; -- the opposite of arsis. 5. (Pros.) (a) The depression of the voice in pronouncing the syllables of a word. (b) The part of the foot upon which such a depression falls., These These ([th][=e]z), pron. [OE. [thorn]es, [thorn][ae]s, a variant of [thorn]as, pl. of [thorn]es, thes, this. See This, and cf. Those.] The plural of this. See This.