To squeal means to make a high-pitched, piercing cry or sound. When someone squeals, they might let out a sharp scream of excitement, fear, or surprise. You might hear a friend squeal with delight when they spot their favorite teacher in the hallway, or squeal in fright when they encounter a spider. Young children often squeal when they're playing tag or getting tickled.

Animals squeal too. Pigs are famous for their squealing sounds, especially when they're excited about feeding time or upset about something. Tires can squeal against pavement when a car stops suddenly, and rusty door hinges sometimes squeal when opened.

The word also has a specific meaning related to telling secrets. When someone squeals on another person, they reveal information that was supposed to stay private, often getting that person in trouble. If a student squeals to the teacher about who started the food fight, they're informing on their classmates. This usage often appears in detective stories, where criminals worry about someone squealing to the police. People who squeal on others this way might be called squealers, though this term can carry a negative tone of betrayal or disloyalty.