Ire is another word for "anger." So if you routinely steal your neighbor's newspaper, don't be surprised to be on the receiving end of his ire.
Ire comes almost directly from the Latin word for anger, ira. While it means pretty much the same thing, ire usually stems from a specific grievance, rather than just general irritation with the world. And if you provoke someone's ire, you're probably going to feel their wrath. Shakespeare used both ire and anger in one famous sentence from his play "Pericles": "Yet cease your ire, you angry stars of heaven!"