Lashon Hara: Lit. the evil tongue. Sins against other people committed by speech, such as defamation, gossip, swearing falsely, and scoffing.
The person who listens to gossip is even worse than the person who tells it, because no harm could be done by gossip if no one listened to it. It has been said that lashon ha-ra (disparaging speech) kills three: the person who speaks it, the person who hears it, and the person about whom it is told. (Judaism 101)