episode

An episode is a narrative unit within a larger dramatic work or documentary production, such as a series intended for radio, television or on-line consumption.
Episode derives from the Greek term (Ancient Greek: ἐπεισόδιον / epeisódion), meaning the material contained between two songs or odes in a Greek tragedy. It is abbreviated as ep (plural eps).
An episode is a coherent narrative unit within a larger dramatic work. It is frequently used to describe units of television or radio series that are broadcast separately in order to form one longer series. An episode is to a sequence as a chapter is to a book. Modern series episodes typically last 20 to 50 minutes in length.