There are several synonyms for the phrase "no longer in use" including obsolete, outdated, deprecated, antiquated, and discontinued. Obsolete describes something that is no longer useful or relevant due to advances in technology or changes in society. Outdated refers to something that is no longer fashionable or current. Deprecated means that something is discouraged or not recommended for use anymore. Antiquated describes something old-fashioned or ancient. Discontinued refers to something that has been taken out of production or use. All of these words can be used interchangeably to describe something that is no longer in use or relevant.