'ion' originates from New Latin/French scientific vocabulary, specifically adopted into scientific English in the early 19th century from the Greek word 'ἰόν' used in descriptions of motion and electrochemical phenomena.

'ion' comes from Greek 'ἰόν' (ion), the present participle of 'ἰέναι' (ienai) meaning 'to go'; the term was repurposed in the 19th century (notably by scientists such as Michael Faraday) to name charged species that 'move' toward electrodes, and then entered modern English scientific usage as 'ion'.

Initially it meant 'going' (the act or state of moving), but over time it evolved into the modern scientific meaning 'a charged particle' (because such particles move toward electrodes in an electric field).