A linguist can be several things, but he or she is usually described as a person who is skilled in some way with a given language, including ancient languages. The term can be used to describe a person who specializes in linguistics, which is the study of language, or it can refer to someone who is well versed in the translation, interpretation, and application of a language. At the same time, this title may be used for someone who is fluent in multiple languages.
In the academic sense, a linguist is a person who engages in and studies linguistics. This is the scientific study of language — both theoretical and practical. Such a person may be studying or professionally practicing either theoretical or applied linguistics.
Examples of theoretical linguistics include grammar, syntax, semantics, origin, and phonetics. Applied linguistics encompasses practical utilization of the knowledge of a language, such as an interpreter, translator, a speech therapist, or a language teacher or professor.
Though the spoken word and written word often intertwine, a linguist typically focuses more on the spoken word than the written word. A polyglot, or person skilled in multiple languages, for example, could be considered a linguist. So may a person skilled in the written word, but this would depend on the length and depth of his or her area of study in linguistics.
There is often some distinction made between linguists themselves, but in the ordinary sense of explanation, the title may be given to any person who is highly educated in both the practical and theoretical elements of one or more given language. There are both associations and professional organizations where a linguist may affiliate with other specialists who share their interests. One such organization is the Chartered Institute of Linguists, which publishes their own magazine.
A linguist differs from a lexiphile, a modern term for someone who loves words, because a linguist is educated in an entire language and not just specific words and has more theoretical knowledge of a language than just an expansive vocabulary.