noun

A thermos is a container that keeps hot things hot and cold things cold. It has a vacuum between the inner and outer layers of the container, which helps to keep the heat or cold from escaping.

Example

1. I put my coffee in a thermos so I can drink it on the way to school.
2. The thermos kept my soup hot all day long.
3. I bought a thermos for my kid so they can have a cold drink on the go.