Use the adjective derisive to describe something or someone that mocks, expresses contempt, or ridicules. You may sometimes catch your kids making derisive comments — especially if you ask them to do chores instead of whatever they think is more important.
Derisive comes from the Latin word deridere, meaning "to ridicule," and is from the roots de-, which means "down," and ridere, which means "to laugh." The adjective derisory comes from the same Latin word, but it has a different sense. If you say something derisive, you show contempt or ridicule, as in a derisive glare at your noisy neighbors. If you say something is derisory, you mean it invites or deserves ridicule or contempt, especially if it is laughably small, such as a derisory diamond chip in an engagement ring.