TETRALOGY
tetralogy
(noun) a series of four related works (plays or operas or novels)
Source: WordNet® 3.1
Etymology
Noun
tetralogy (plural tetralogies)
A set of four works of art that are connected, and that can be seen either as a single work or as four individual works. They are commonly found in literature, film, or video games.
(historical) A group of four dramas, three tragic and one satiric, exhibited together at the festivals of Dionysus at Athens.
(medicine) A combination of four symptoms.
(medicine, colloquial) Tetralogy of Fallot.
Synonyms
• (four related works): quadrilogy (nonstandard)
Source: Wiktionary
Te*tral"o*gy, n. Etym: [Gr. Tetra-) + tétralogie.] (Gr. Drama)
Definition: A group or series of four dramatic pieces, three tragedies and
one satyric, or comic, piece (or sometimes four tragedies),
represented consequently on the Attic stage at the Dionysiac
festival.
Note: A group or series of three tragedies, exhibited together
without a fourth piese, was called a trilogy.
Source: Webster’s Unabridged Dictionary 1913 Edition