Greek word meaning A play in which the main character suffers?

The Greek word you're looking for is τραγωδία (tragōdia). While it doesn't literally mean "a play in which the main character suffers," that's the core concept behind its meaning. It translates directly to "goat song," referencing the ancient Greek practice of sacrificing a goat during the performance, but the meaning evolved to signify a play dealing with serious and often tragic themes, typically involving the downfall of a noble protagonist.