This summer I enlarged my vocabulary while participating in an online film course. Among the words new to me are diegesis [DYE-uh-JEE-sis] and diegetic [DYE-uh-JET- ik].
The terms are barely a blip on the Ngram Viewer until the 1970s, when they were introduced into the context of film studies in 1973 by an essay written by a French film critic in the journal Screen.
Diegesis does have an OED citation previous to 1973, but only one, dated 1829:
The Diegesis, being a Discovery of the Origin, Evidences, and Early History of Christianity.
Diegesis comes from a Greek word meaning narration or narrative.
In the context of film studies, diegesis denotes the story of the movie. The diegesis includes the fictional time, place, characters, and events that make up the universe portrayed.
Diegetic is an adjective that means “pertaining to diegesis.” The most frequent use of diegetic that I’ve seen so far is in the term “diegetic sound.”
Sound that originates within the action of the story is diegetic sound. For example, when Spock plays his Vulcan harp in a Star Trek episode, the sound of the harp is diegetic. The characters in the story can hear it.
The spooky music that signals something bad about to happen to the landing party is non-diegetic sound. It exists outside the story. The viewer hears it, but not the characters.
Here are examples of the use of diegesis and its forms in critiques of film and written literature:
In the film [Children of Men], sound supports this vision by remaining for the most part diegetic, emerging as everyday sounds of street noise, chaos, sirens, conversations, overheard music, and so forth.
During After Hours, Scorsese appears diagetically in Club Berlin wearing a military uniform…. Like the diegetic appearances by Scorsese in Taxi Driver, Raging Bull and The King of Comedy, the moment works reflexively in terms of Scorsese’s extra-diegetic role as director.
The embedded worlds may be more or less continuous with the world of the primary diegesis, as in Wuthering Heights, or they may be subtly different, as in the play-within-the-play of Hamlet.
I’ve even seen the term used in reference to a video game in which the “non-diegetic element” is a line of informational text that pops up on the screen, interfering with play:
The non-diegetic elements fade in and out, out of the player’s control, which of course results in a complete lack of control for the player.