What is another word for "expositor"?

Roget's Thesaurus (1911) lists these synonyms for "expositor": abecedarian, adviser, annotator, apostle, bear, chalk, cicerone, clergy, coach, commentator, courier, crammer, dame, demonstrator, director, disciplinarian, dominie, don, dragoman, dry, duenna, example, explainer, exponent, expounder, for, glossarist, governess, governor, grinder, guide, guru, imitation, institutor, instructor, interpreter, leader, lecturer, master, mentor.