Cork (noun)

1. The outer bark of the cork oak, used for stopping bottles, sealing jars, and making floats and insoles.
2. A small piece of cork used as a float for fishing or as a marker on a map.
3. The stopper of a bottle or other container, typically made of cork.

Origin:

Middle english: from old french corque, from medieval latin corca, perhaps of celtic origin.

Examples:

1. He opened the bottle by removing the cork.
2. She used a cork to seal the jar.
3. A cork was used to make the fishing float.
4. He used a cork to mark his location on the map.
5. The cork was used as an insulation material.