docent

Instructive; that teaches.

A teacher or lecturer at some universities (in central Europe, etc.)

Zermelo had been a docent at Göttingen when Kit was there and, like Russell, had been preoccupied with the set of all sets that are not members of themselves.

A tour guide at a museum, art gallery, historical site, etc.

The docent greeted the visitors and welcomed them to the Smithsonian.

She was listening distractedly as an elderly docent intoned to a circle of listless children.