Hybris is one of those
words that cannot be easily translated into any other
language, but since the
word, and
concept it represents, are so essential to
Greek culture and way of thinking, I'm going to anyway.
Hybris might be translated as 'excessive pride', but it is more than that. It is the will of a man (or woman) to surpass his (or her) alotted destiny, the destiny of mankind, and the will to be better (or equal) to the gods.
Boasts about being better than the gods (or a god) are also considered hybris, and as such, the person who sins in it will be punished by the gods.
Fear of hybris dominated much of the life of the Greeks, for instance, the Greeks hardly ever built bridges, because bridges were considered a double hybris: they shackled the river (almost always a god by his own right), and connected what the gods chose to seperate.
In his "History" Herodotus attributes Xerses defeat in the Persian War to hybris, not only did Xerses want to rule over two continents (Asia and Europe) he also built a bridge over the bosphorus!
Apollo is the god that usually punishes over such crimes and does so with extreme cruelty.
Classic examples of hybris in Greek myth are the stories of Niobe and Marsias.
Hybris is also the daimon that is responsible for this sin.