1. an institution for popular education providing discussions, lectures, concerts, etc.
2. a building for such activities.
3. (initial capital letter) the gymnasium where Aristotle taught, in ancient Athens.
4. a lycée.
No wonder I was desirous of knowing, long before the opportunity was afforded me, how far these valuable purposes were accomplished by the frequenters of Mrs. Carter’s lyceum. — Charles Brockden Brown, Alcuin, 1798
I don’t recall the surname. We’d just been to the Lyceum to see Sarah Bernhardt onstage. — Johanna Moran, The Wives of Henry Oades, 2010
Originally the Lyceum was a place in Athens named for the neighboring temple of Apollo, the god of music and poetry. The word lýkeios was used as an epithet of Apollo, and the name became associated with the place. Over time the name was extended to educational venues of any sort.