A rack is a frame or stand designed to hold, organize, or display things. A bike rack holds bicycles upright so they don't fall over. A spice rack keeps small jars organized in your kitchen. Clothing stores use racks to display shirts and jackets. The key idea is storage that keeps items accessible and organized.

As a verb, rack can mean to cause great physical or mental pain. When someone is racked with pain, they suffer intensely. Someone might be racked by guilt after doing something wrong, feeling tormented by their conscience. A terrible cough can rack your whole body. This meaning suggests suffering that shakes or strains you.

To rack your brain means to think very hard trying to remember or solve something. If you're racking your brain trying to recall where you left your homework, you're searching your memory intensely, almost painfully.

In pool or billiards, to rack the balls means to arrange them in the triangular frame at the start of a game. The wooden triangle that holds the balls is also called a rack.