Exhausting describes something that drains your energy and leaves you feeling worn out and tired. An exhausting day might include a challenging math test, soccer practice in hot weather, and hours of homework. By bedtime, you feel completely drained.

Physical activities like running a marathon or climbing a mountain are exhausting because they use up your body's energy. But mental work can be just as exhausting: solving difficult problems for hours, taking multiple tests in one day, or concentrating intensely on a complex project can tire out your brain.

Emotional experiences can be exhausting too. A long argument with a friend, worrying about a big presentation, or dealing with a stressful situation can leave you feeling depleted even if you haven't moved from your chair.

When you're exhausted, you've used up your available energy. Notice that exhausting describes the thing that tires you out (an exhausting hike), while exhausted describes how you feel afterward (feeling exhausted).