exposition

noun

• The action of exposing something to something, such as skin to the sunlight.
• (authorship) The act or process of declaring or describing something through either speech or writing; the portions and aspects of a piece of writing that exist mainly to describe the setting, characters and other non-plot elements.

  "My reviewer said she couldn't picture the setting for my story, so I'm improving the exposition."

• The act of expulsion, or being expelled, from a place.
• An event at which goods, artwork and cultural displays are exhibited for the public to view.

  "The first prototype was unveiled at an exposition."

• (authorship) An essay or speech in which any topic is discussed in detail.

  "I turned my research into an exposition on the traditional music of Borneo."

• (authorship) An opening section in fiction, in which background information about the characters, events or setting is conveyed.
• The opening section of a fugue; the opening section of a movement in sonata form
• The abandonment of an unwanted child.