scholiast

英 ['skəʊlɪæst] 美['skolɪəst]

1. a scholar who writes explanatory notes on an author (especially an ancient commentator on a classical author)

scholiast (n.): "one who writes explanatory notes upon a classical writer," 1580s, from Late Latin scholiasta, from Late Greek skholiastes, from skholiazein, from skholion "explanatory note or comment," from skhole (see school (n.1)). Related: Scholiastic.