Before revision: A group of languages that descend from a common ancestor is known as a language family; in contrast, a language that has been demonstrated to not have any living or non-living relationship with another language is called a language isolate.
After revision: A group of languages that descend from a common ancestor is known as a language family; in contrast, a language that has been demonstrated not to have any living or non-living relationship with another language is called a language isolate.