A "hiss" is a sharp, sibilant sound often made by animals like snakes or cats. It can signal warning or displeasure, letting others know to stay away. For example, when a cat feels threatened, it might hiss to scare off an intruder. This sound is created by forcing air through a narrow opening, producing a distinctive noise that can be quite startling. In addition to animals, humans can also hiss, often to express disapproval or to get someone's attention. For instance, during a performance, an audience might hiss to show they dislike something. This sound can convey strong emotions, making it a powerful form of communication.