Here's an example:
A person eminently skilled in something, as an occupation, art or science, a person whose teachings others accept or follow; a Zen master. the great masters of the Impressionist period.
"A massive open online course (MOOC) is an online course aimed at large-scale interactive participation and open access via the web. In addition to traditional course materials such as videos, readings, and problem sets, MOOCs provide interactive user forums that help build a community for the students, professors, and teaching assistants"