means A large enclosed venue, typically open-air with banked seating, built to host sporting events or concerts before big crowds.

from From Latin 'stadium,' borrowed from Greek 'stadion'—which was both a foot-race and the track it was run on, and also a unit of distance (roughly 185 metres, the length of that race). The Greek word may be tied to 'spadion,' from a verb meaning 'to draw' or 'stretch,' fitting for a stretch of ground you sprint across. So the modern bowl of roaring fans descends, fittingly, from an ancient running lane.