'ballpark' originates from the English words 'ball' and 'park', where 'ball' referred to a spherical object used in games and 'park' referred to a large public green area.

'ballpark' was initially used to describe a place where ball games were played and eventually became a term for an approximate range.

Initially, it meant 'a place for playing ball games', but over time it evolved into its current meaning of 'an approximate range or estimate'.