To shut means to close something, usually by moving a part into position to block an opening. When you shut a door, you swing it closed until it latches. When you shut a book, you bring the covers together. You can shut your eyes, shut a window, or shut a drawer.

The word often suggests closing something firmly or completely, with a sense of finality. If someone tells you to shut the gate behind you, they want it fully closed so nothing can get through. Shut sounds more decisive than simply “close”: you might gently close a door when someone's sleeping, but shut it firmly when you want privacy.

People also use shut to mean stopping something from operating. A business can shut down when it stops running, permanently or temporarily. During a snowstorm, schools might shut for the day.

The phrase shut up means to stop talking (though it's considered rude to say this directly to someone). If you shut out distractions while studying, you block them from your awareness. When something is shut off, like water or electricity, it stops flowing or working.