'cation' originates from New Latin/modern scientific coinage built from Greek elements, specifically from Greek roots 'kathodos' and 'ion', where 'kath-' meant 'down' (as in 'kathodos' = 'down way') and 'ion' meant 'going'.

'cation' was coined in the 19th century in the context of electrochemistry to name ions that move toward the cathode; formed from Greek elements and adopted into scientific Latin/English usage, it became the standard term in modern chemistry.

Initially it meant 'an ion that moves toward the cathode', but over time it has come to be used more specifically for 'a positively charged ion'.