A classical language is a language with a literature that is classical. According to UC Berkeley linguist George L. Hart, "it should be ancient, it should be an independent tradition that arose mostly on its own, not as an offshoot of another tradition, and it must have a large and extremely rich body of ancient literature."

Classical languages are typically dead languages or show a high degree of diglossia, as the spoken varieties of the language diverge further away from the classical written language over time.