ex·po·si·tion 
(ĕk′spə-zĭshən)
(ĕk′spə-zĭshən)n.
1. A setting forth of meaning or intent.
2.
a. A statement or rhetorical discourse intended to give information about or an explanation of difficult material.
b. The art or technique of composing such discourses.
3. Music
a. The first part of a composition in sonata form that introduces the themes.
b. The opening section of a fugue.
4. The part of a play that provides the background information needed to understand the characters and the action.
5. An act or example of exposing.
6. A public exhibition or show, as of artistic or industrial developments.
[Middle English exposicioun, from Old French exposition, from Latin expositiō, expositiōn-, from expositus, past participle of expōnere, to expound; see EXPOUND.]
ex·posi·tive (ĭk-spŏzĭ-tĭv), ex·posi·to′ry (-tôr′ē) adj.
ex·posi·tor n.