v.1. To become cooler: We sat in the shade to cool down. As soon as the pie cools down, we can eat it.
2. To make something cooler: She cooled down her coffee with an ice cube. He turned on the fan to cool the room down.
3. To gradually relax after a period of physical exertion: We walked around the track to cool down after our two-mile run.
4. To become less angry or contentious: Let's discuss this after you cool down a bit.
5. To cause someone or something to become less angry or contentious: The mediator cooled down the disputing parties. The principal cooled the angry students down.