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.
Four plays performed together in sequence. In ancient Greek theatre, this was the basic pattern for the tragic playwrights, who presented a trilogy of tragedies, followed by a satyr play.
a series of four related works (plays or operas or novels)
a complex of four conditions
a compound work that is made up of four (Greek tetra) distinct works
Greek tetra = four, and logos = discourse, hence a combination of four elements e.g., symptoms or defects.
group of four plays presented by a tragic playwright at the City Dionysia, composed of three tragedies and a satyr play. In Aeschylus' time, tetralogies were often composed on a single theme; by the time of the preserved plays of Sophocles and Euripides, this practice seems to have been largely abandoned.