To deride means to mock or make fun of someone in a harsh, contemptuous way. It's more cutting than gentle teasing between friends. When people deride something, they express scorn and disrespect, trying to make it seem worthless or ridiculous.

Imagine a student working hard on an art project, and classmates deride their effort by laughing cruelly and calling it ugly. That's derision: mocking designed to hurt and diminish. Politicians sometimes deride their opponents' ideas instead of debating them fairly. A critic might deride a movie as terrible, using sarcastic and contemptuous language.

The related noun is derision, which describes the mocking itself. If your idea is met with derision, people are laughing at it scornfully rather than considering it seriously. Derisive is the adjective form: a derisive laugh or derisive comment carries that same contemptuous mockery.

Derision differs from honest criticism or playful joking. When you deride something, you're not trying to help improve it or share a laugh together. You're trying to tear it down and make others see it as laughable. It's a weapon disguised as humor, and it can reveal more about the person doing the mocking than about whatever they're mocking.