A coaster may refer to any of the following:
1. Coaster is common slang used for either an AOL compact disc or a compact disc that is no longer good, either because of scratches or because of a failure during its creations. The term coaster comes from the coaster commonly used to keep watermarks from being made on tables from drinks.
2. A coaster can also used to describe recordable discs that have become bad after a burn has failed.