Where does “Gymnasium” come from?

Gymnasium (Latin) comes from Ancient Greek γυμνάσιον, from Ancient Greek γυμνάζω, from Ancient Greek γυμνός, from Proto-Hellenic *gʷomnós.

Ancestry of “Gymnasium”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	γυμνάσιον	bodily exercises; gymnastic school, school
2	Ancient Greek	γυμνάζω	to train naked; to train
3	Ancient Greek	γυμνός	naked, nude, unclad; unarmed, without armor,...
4	Proto-Hellenic	*gʷomnós	—

Gymnasium — Etymology, Origin & Word History | Etymology Explorer