1. verb To cease burning (as of something that is on fire). Get the birthday girl in here before the candles on her cake burn out! At this point, the firefighters are just going to let the fire burn out.

2. verb To stop working properly, often through overheating. In this usage, a reflexive pronoun can be used between "burn" and "out." Unfortunately, I think the motor in your lawn mower has burned out. We have to repair the engine before it burns itself out.

3. verb To hollow out by fire, as of a building. The fire completely ravaged and burned out our beloved home.

4. verb To force someone to leave a place by setting it on fire. During their attack, the troops burned out everyone in the town.

5. verb To overwork or exhaust someone or oneself, especially to the point of no longer being able to maintain a particular level of performance or dedication. In this usage, a reflexive pronoun is often used between "burn" and "out." If you keep staying up so late working on this report, you're going to burn yourself out. Don't burn out your interns by making them come in every day.

6. noun One who is apathetic and unmotivated, especially an employee. When used as a noun, the phrase is usually written as one word. We need to hire some hard workers and get rid of these burnouts who collect a paycheck for doing nothing.

7. noun, slang A regular drug user or addict who displays the adverse effects of drug use, especially cognitive impairment. When used as a noun, the phrase is usually written as one word. You can't dismiss these students just because they're burnouts—they clearly need help and guidance.