Is pope infallible according to catholicizm?

Not really, the pope is just as fallible as any other human being in almost every aspect of his life, but ONLY when he makes ecumenical judgments in his capacity as a pope does God guide those judgments. It's the same sort of belief that protestants have about the inerrancy of the scripture, God guides the hand or voice of the pope like God guided the pen of the apostles when they wrote the text, that didn't stop them messing up in other areas of their lives.