A rim is the outer edge or border of something, especially something circular or curved. The rim of a cup is where your lips touch when you drink. The rim of a basketball hoop is the orange metal circle the ball must pass through to score. The rim of a canyon, like the Grand Canyon, is the dramatic edge where flat ground suddenly drops away into a vast chasm below.

The word often suggests a raised or defined border that marks where something ends. When you wear rimmed glasses, a frame surrounds each lens. If you fill a glass to the rim, you've poured liquid right up to the top edge.

In basketball, players talk about shots that hit the rim, bounce off the rim, or rim out when the ball circles the edge but won't fall through. Bicycle wheels have rims that hold the tire in place. The word captures that crucial boundary where one thing meets another, whether it's your hot chocolate meeting the air, a basketball meeting the hoop, or solid ground meeting empty space.