According to Aristotle, the cause of the tragic hero or heroine's suffering is hamartia, also known as tragic flaw. It is some sort of a mistake in a character, that inevitably leads to their death in ancient Greek dramas.
Desis is literally translated as tying, it is everything in a play that leads up to peripeteia.
On the other hand, lusis is translated as untying, it is a denouement.
Dithyramb is a type of a poem dedicated to Dionysus, Greek god of wine.