To constrict means to squeeze something tightly or make it narrower, like when you wrap your hand around a garden hose and watch the water spray out faster through the smaller opening. When something constricts, it becomes tighter or more compressed.

Boa constrictors got their name because they wrap their powerful bodies around prey and squeeze. Your blood vessels constrict when you're cold, getting narrower to keep warmth near your body's core. That's why your fingers and toes feel coldest: less blood can flow through the constricted vessels. A tight collar might constrict your neck uncomfortably, making it harder to swallow or breathe freely.

The word often describes an unwanted tightness or limitation. Fear can make your chest feel constricted, as if your lungs can't expand fully. Rules that are too strict might constrict your freedom to make choices. When doctors say your airways are constricted during an asthma attack, they mean the tubes carrying air to your lungs have gotten too narrow, making breathing difficult.

The opposite of constrict is dilate or expand: your pupils constrict in bright light but dilate in darkness.