Tired means lacking energy or strength because you need rest. When you're tired, your body and mind have worked hard and need time to recover. After a long day at school, a tough soccer practice, or staying up late reading, you might feel tired: your eyelids get heavy, your thoughts move slowly, and your body just wants to sink into a soft chair.

Being tired is your body's way of saying it needs a break. Sleep recharges you like plugging in a phone overnight. Some tiredness comes from physical activity, like feeling tired after swimming laps. Other tiredness comes from mental work, like feeling tired after concentrating hard on a difficult math test.

The word can also describe being weary of something that's gone on too long. If your little brother tells the same joke for the twentieth time, you might say “I'm tired of hearing that joke.” When people are tired of waiting, or tired of the same routine, they're not necessarily sleepy, but they're worn out from repetition or frustration.

Being tired occasionally is normal and healthy. It reminds you to rest. But if someone feels tired all the time despite sleeping well, that might signal they need to talk to a doctor.