Coalbin is a term used to refer to a container used to store coal. It is often seen in older homes and buildings. However, there are several other terms that can be used as synonyms for coalbin. These include coal bunker, coal cellar, coal vault, coal house, and coal shed. These terms are used interchangeably to refer to a structure that is used to store coal. While coalbin may be the most commonly used term, the others are just as accurate and describe the same structure and function. So whether you refer to it as a coalbin or coal bunker, the purpose remains the same - to store coal for heating purposes.