A cooler is an insulated container designed to keep food and drinks cold, usually filled with ice or ice packs. When your family packs a cooler for a beach trip or picnic, you're creating a portable refrigerator that keeps sandwiches fresh and drinks refreshing for hours. The thick walls and tight lid trap the cold air inside, slowing down the melting of ice and preventing warm outside air from getting in.

Coolers come in many sizes, from small lunch-box versions to enormous ones that can hold enough supplies for a week-long camping trip. Some have wheels and handles for easy transport. The invention of portable coolers in the 1950s changed how families could enjoy outdoor activities, since people could finally bring perishable food safely to places without electricity.

The word can also describe something or someone that's cooler than something else, the comparative form of cool. Your older sibling might seem cooler than you because they know more about music or sports. A winter morning might feel cooler than the previous day. In this sense, it simply means more cool, whether referring to temperature or to someone's impressive, confident style.