Merriam-Webster Collegiate Dictionary - thesis

 noun  (plural theses)  Etymology: in sense 1, Middle English, lowering of the voice, from Late Latin & Greek; Late Latin, from Greek, downbeat, more important part of a foot, literally, act of laying down; in other senses, Latin, from Greek, literally, act of laying down, from tithenai to put, lay down — more at do  Date: 14th century  1.  a.  (1) the unstressed part of a poetic foot especially in accentual verse  (2) the longer part of a poetic foot especially in quantitative verse  b. the accented part of a musical measure ; downbeat — compare arsis  2.  a. a position or proposition that a person (as a candidate for scholastic honors) advances and offers to maintain by argument  b. a proposition to be proved or one advanced without proof ; hypo~  3. the first and least adequate stage of dialectic — compare syn~  4. a dissertation embodying results of original research and especially substantiating a specific view; especially one written by a candidate for an academic degree