The ancient HIPPODROME was an open-air stadium with an oval track used for horse and chariot racing. Hippos = horse and Dromos = race.
Okay ... here’s a brain teaser for you ... if Hippo means horse, why are modern hoses-riders called Equestrians? I guess the short answer would be that modern horse-riders are not too smart and use the Latin word for horse instead of the much cooler Greek word Hippo ... I mean really ... which sounds better: Equestrian or Hippoestrian? I rest my case!