scholiast

/ˈskoʊliˌæst/
noun
  1. A person who writes explanatory notes or comments on ancient texts, especially classical Greek or Latin works.
    • The scholiast added notes to the margins of the ancient play to explain its references.
    • A scholiast from the Byzantine period commented on Aristotle's writings.
    • Modern scholars rely on the work of ancient scholiasts to understand difficult passages.