The Spanish word 'estadío' comes from the Latin word 'stadium', which meant both a race course and a measure of length. The Latin word was borrowed from Ancient Greek 'stadion' (στάδιον), which similarly referred to both a fixed measure of distance and a race course where athletes would compete. The Spanish word developed with the addition of an initial 'e-' (a common development in Spanish words borrowed from Latin that began with 's' + consonant) and maintains the meaning related to a sports venue or stadium.

A closely related and more common Spanish word is 'estadio' (without the accent), which is the modern standard form meaning 'stadium'. The word 'estado' (meaning 'state' or 'condition') is also somewhat related, as both words ultimately derive from Latin words referring to standing or established places, though they developed distinct meanings over time.

The English word 'stadium' is directly related to 'estadío', as both come from the same Latin root 'stadium'. The English word 'stage' is also distantly related, as it developed from the same Indo-European root meaning a place where one stands. You can remember the connection by thinking about how a stadium is essentially a grand stage for sporting events.