Learn how to say Stadium correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word stadium:
noun (plural stadiums or stadia /ˈsteɪdɪə/)
1an athletic or sports ground with tiers of seats for spectators.
(in ancient Rome or Greece) a track for a foot race or chariot race.
2 (plural stadia) an ancient Roman or Greek measure of length, about 185 metres (originally the length of a stadium).
late Middle English (in sense 2): via Latin from Greek stadion. Sense 1 dates from the mid 19th century
The plural of stadium can be spelled either stadiums or stadia (like the original Latin).