a proposition that a person offers to support and substantiate by argument
a proposition to be proved or one advanced without proof; a hypothesis
in philosophy, the first stage of a reasoned argument presenting the case: compare antithesis, synthesis
a dissertation embodying the results of original research; specif one submitted for a doctorate in Britain
the unstressed part of a metrical foot: compare arsis
[via Latin from Greek thesis act of laying down, from tithenai to put, lay down]