The term "listener-in" refers to a person who eavesdrops or listens in on private conversations. There are several synonyms for this term, such as eavesdropper, snooper, spy, listener, overhearer, and wiretapper. These words all have negative connotations, implying a breach of privacy and trust. It is important to remember that listening in on private conversations without consent is not only morally wrong but illegal. Instead, one should practice active listening and engage in respectful, honest communication with others. Being a good listener involves actively paying attention, empathizing with others, and showing genuine interest in what others have to say.