A "harbinger of doom" refers to a sign or omen that indicates impending disaster or misfortune. This term is often used in literature and folklore to describe events, creatures, or phenomena that foreshadow negative outcomes. For example, a dark storm cloud might be seen as a harbinger of doom for an upcoming outdoor event. In popular culture, various symbols serve as harbingers of doom, such as ravens or black cats. These symbols can evoke feelings of fear or anxiety, suggesting that something bad is about to happen. Understanding these signs can help individuals prepare for potential challenges or dangers.