What’s a lyceum?

Good question. We defer to the Oxford English Dictionary:

1. (With capital initial.) The proper name of a garden with covered walks at Athens, in which Aristotle taught his philosophy. Hence, the Aristotelian philosophy and its adherents.

2. Used allusively as the proper name of certain places of study or instruction.

c. U.S. An institution in which popular lectures are delivered on literary and scientific subjects.”