docent

noun

privatdocent.
a college or university lecturer.
a person who is a knowledgeable guide, especially one who conducts visitors through a museum and delivers a commentary on the exhibitions.

noun

a voluntary worker who acts as a guide in a museum, art gallery, etc
(dəʊˈsɛnt, German doˈtsɛnt) (in the US) a lecturer in some colleges or universities

adj.

1630s, from Latin docentem (nominative docens), present participle of docere “to teach” (see doctor). As a noun, from 1880.