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

Roget 524: interpreter; expositor, expounder, exponent, explainer; demonstrator.    scholiast, commentator, annotator; metaphrast^†, paraphrast^†; glossarist^†, prolocutor.    spokesman, speaker, mouthpiece.    dragoman, courier, valet de place, cicerone, showman; oneirocritic^†; (Edipus; oracle) &c.. 513 ... show more

Polish: scholiasta