The Spanish word 'catarata' comes from Latin 'cataracta', which meant both 'waterfall' and an eye condition. The Latin term was borrowed from Ancient Greek 'kataraktes' (καταράκτης), meaning 'waterfall' or literally 'that which strikes downward'. The Greek word was formed by combining three elements: 'kata-' (κατά) meaning 'down' or 'towards', the verb 'arassein' (ἀράσσειν) meaning 'to strike', and the agent suffix '-tes' (-της).

The connection between waterfalls and the eye condition (cataract) comes from the ancient conception of the eye condition as a kind of 'waterfall' or membrane falling across the eye, blocking vision - similar to how a waterfall is water falling down across a surface.

While 'catarata' itself is a relatively common Spanish word, there aren't many simpler Spanish words that share its Greek origins. However, the prefix 'cata-' appears in other Spanish words like 'catástrofe' (catastrophe) and 'catálogo' (catalog), though these follow different semantic developments.

The English word 'cataract' is directly related to Spanish 'catarata', as both come from the same Latin and Greek origins. Like Spanish, English maintains both meanings: a large waterfall and the eye condition. The word 'catastrophe' also shares the same Greek prefix 'kata-' meaning 'down', though it developed along a different path to mean a sudden disaster.