from The Century Dictionary.
- noun The school in which the chorus of the Greek drama was trained.
- noun The space where the choral dance was performed.
Sorry, no etymologies found.
The "choragium" was the dress and furniture, or "properties" for the stage, supplied by the
The Captiva and the Mostellaria Titus Maccius Plautus 1847
So we stood, then, beneath the starless sky, listening to the rich _choragium_ of the "World's End."
Let thy thoughts be of things which have not entred into the hearts of beasts: think of things long past, and long to come: acquaint thyself with the choragium  of the stars, and consider the vast expansion beyond them.
Christian Morals 1605-1682 1863