What does the prefic epi mean?

Epi- is a prefix used in English to indicate something on the surface or outer part of something. It can be used in scientific terms, such as epidermis (the outermost layer of skin) or epicenter (the point on the surface of the Earth directly above the focus of an earthquake), as well as in everyday language, such as episode (a distinct part of a story or event) or epiphany (a sudden moment of realization).