The noun exposition has 4 senses (first 1 from tagged texts)
1. (2) exposition, expounding -- (a systematic interpretation or explanation (usually written) of a specific topic)
2. exhibition, exposition, expo -- (a collection of things (goods or works of art etc.) for public display)
3. exposition -- (an account that sets forth the meaning or intent of a writing or discourse; "we would have understood the play better if there had been some initial exposition of the background")
4. exposition -- ((music) the section of a movement (especially in sonata form) where the major musical themes first occur)