Thirst is the uncomfortable feeling that tells you your body needs water. When you're thirsty, your mouth feels dry, your throat might feel scratchy, and you think about nothing but getting a drink. After running around on a hot day or eating salty popcorn at the movies, you'll feel thirst urging you to find water.

Your body is remarkably smart about monitoring itself. When you start losing water through sweat, breathing, or just normal activity, your brain notices and creates that thirsty feeling. It's one of your body's most important warning systems, like how hunger tells you that you need food. Ignoring thirst for too long leads to dehydration, which can make you feel weak, dizzy, and confused.

The word also describes a strong desire for something beyond water. Someone might have a thirst for knowledge, reading every book they can find about ancient Egypt. An athlete might have a thirst for victory, practicing extra hours to improve. A thirst for adventure might send an explorer to distant lands. When you use thirst this way, you're comparing an intense craving or ambition to that powerful physical need for water, when nothing else will satisfy you until you get what you're seeking.

As a verb, thirst means to feel thirsty or to strongly want something. You might thirst for water after a long hike, or thirst for answers when a mystery doesn’t make sense yet.