Exhausted means completely drained of energy, so tired that you feel like you can barely move or think clearly. After running a long race, playing hard all day, or staying up late finishing a big project, you might feel exhausted: your muscles ache, your mind feels foggy, and all you want to do is rest.

The word comes from the idea of being emptied out, like a fuel tank that's run completely dry. When you're just tired, you still have some energy left. When you're exhausted, it feels like every bit of energy has been used up. A marathon runner crossing the finish line might collapse, exhausted. A student who stayed up all night studying might feel mentally exhausted during the test, struggling to focus even though they know the material.

You can also exhaust other things besides yourself. A hiker might exhaust their water supply on a long trail. A detective might exhaust all possibilities when searching for clues, meaning she has checked every option she can think of. When something is exhausted, whether it's your energy, a resource, or a list of options, it means you've used it all up and there's nothing left.