'arcadia' originates from Greek, specifically the word 'Arkadía', where 'Arkas' was the name of a mythic ancestor associated with the region.

'arcadia' changed from Ancient Greek 'Arkadía' into Latin 'Arcadia', passed into Medieval and Renaissance usage (e.g. Middle English/older forms 'Arcadie' or 'Arcady') and eventually became the modern English word 'arcadia'.

Initially, it meant 'the geographical region of Arcadia' (and its mythic associations), but over time it evolved into its current broader meaning of 'an idealized rural paradise' used in literature and everyday language.