I am sorry to say that yesterday's daily Match Up word game from the "Free Dictionary" included a misleading and inaccurate synonym. The word in the left column was polyglot and the answer in the right column was linguist. While polyglots are generally considered linguists, linguists are not necessarily polyglots and for a pair of words to be true synonyms they should be interchangeable; that is not the case here. The definitions found on the "Free Dictionary" website don't even support the synonymity of linguist and polyglot. These definitions are as follows:
Synonym: A word having the same or nearly the same meaning as another word or other words in a language.
Linguist: A person skilled in the science of language. Also linguistician.
Polyglot: A person having a speaking, reading, or writing knowledge of several languages.
In sum, as these definitions indicate, a person can be skilled in the science of language without speaking many languages (or even two languages for that matter). Semantically this is called lack of entailment because being a linguist does NOT entail being a polyglot.