Hysterics means wild, uncontrolled emotion, usually laughter or panic that someone can't stop. When your friend gets the giggles during a serious moment and literally cannot stop laughing, even when the teacher gives them a warning look, they're in hysterics. When someone panics so completely that they're crying, shouting, and can't calm down, they've also dissolved into hysterics.

The word often describes emotions that have spiraled beyond someone's control. A person in hysterics isn't choosing to act that way. They've lost their grip on their composure, whether from something hilarious, terrifying, or overwhelming. You might see someone go into hysterics after receiving shocking news, or after watching the funniest video they've ever seen.

Today, hysterics usually refers to uncontrollable laughter. When someone says a comedy show “had the audience in hysterics,” they mean people were laughing so hard they could barely breathe.

A related word is hysterical, which can mean extremely funny (“That joke was hysterical!”) or wildly emotional and out of control (“She was hysterical with fear”).