\Te*tral"o*gy\, n. [Gr. ?; te`tra- (see {Tetra-}) + ?
a speech, discourse: cf. F. t['e]tralogie.] (Gr. Drama)
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.