Tetralogy

[Sarah]

A group or series of four dramatic pieces, three tragedies andone satyric, or comic, piece (or sometimes four tragedies),represented consequently on the Attic stage at the Dionysiacfestival.

[Sarah]

The word overly sensitive linguists and people with a fixed attitude to language use (or pretensious posh people) use instead of quadrilogy, because quadrilogy is a mixture of Latin and Greek and therefore awfully awkward to say, darling.
Tetralogy is a word that means a