To extinguish means to put out a fire or light completely. Firefighters work to extinguish blazes that threaten homes and forests. You extinguish a candle by blowing it out or covering it with a snuffer that cuts off its oxygen supply. When you turn off a lamp, you could say you've extinguished its light, though people usually save this word for flames.

The word also means to end or destroy something completely. A country might try to extinguish a rebellion. A new invention might extinguish an old industry, the way cars nearly extinguished the buggy-whip business. When someone's hopes are extinguished, they've lost all optimism about something they cared about deeply.

Notice how extinguish suggests total elimination, not just temporary reduction. You don't extinguish a fire by making it smaller; you eliminate it entirely. The related word extinguisher refers to a device that puts out fires, like the red fire extinguishers you see hanging on school walls. These tools work by smothering flames with chemicals that remove oxygen, which fires need to burn.