'banky' originates from English, specifically from the noun 'bank' (ultimately from Old Norse 'banki' and/or Old Italian 'banca'), where 'bank' meant 'bench' or 'mound' and the English suffix '-y' meant 'characterized by or having the quality of'.

'bank' changed from Old Norse 'banki' (and via Old Italian 'banca' in the sense of a bench used by money changers) into Middle English 'bank(e)' and eventually modern English 'bank'; the adjective 'banky' was formed in English by adding the productive suffix '-y' to 'bank'.

Initially, 'bank' referred to a 'bench' or 'mound'; over time it came to mean both a financial institution and a natural or man-made slope ('river bank', 'embankment'); 'banky' evolved to describe the quality of having a bank or of being sloped (and by extension, informally, 'bank-like').