"Dead Letters" refers to mail that cannot be delivered to the intended recipient due to various reasons, such as an incorrect address or the recipient being unknown. These letters are typically collected by postal services and held for a certain period before being returned to the sender or disposed of. In some cases, "Dead Letters" can also refer to a literary or artistic concept, where messages or communications remain unacknowledged or unanswered. This theme is often explored in literature and film, highlighting the emotional weight of unexpressed thoughts and feelings, as seen in works by authors like Franz Kafka or Virginia Woolf.