What does the term "obsolete" specifically refer to in language?

The term "obsolete" in the context of language refers specifically to words that have become completely out of use. This means that they are no longer employed in modern language for communication and are not commonly understood by speakers of the language today. Obsolescence in language can occur for various reasons, including cultural shifts, technological advancements, or changes in social practices, which render certain words unnecessary or irrelevant.

In contrast, the other choices describe different aspects of language. Words that have lost their meaning can still be present in texts or conversation but have no significance; archaic words still have some use but may not be familiar to all speakers; and words with multiple meanings indicate linguistic richness and complexity rather than obsolescence. Thus, the focus on complete lack of use accurately captures what "obsolete" means in the realm of language.