a sports ground surrounded by tiers of seats for spectators
in ancient Greece and Rome, a course for foot races or chariot races, surrounded by tiered seats
(pl stadia) any of various ancient Greek and Roman units of length, usu of about 185m (about 202yd)
a stage or period of development, e.g. between successive moults in the development of an insect, or in the progress of a disease
[Middle English via Latin stadium from Greek stadion racecourse, unit of length, alteration of spadion, from span to pull]