'scheme' originates from Modern Latin/Greek via Old French and Latin; ultimately from Greek 'skhēma' (σχῆμα), where 'skhē-' meant 'to have form' or 'shape'.

'scheme' changed from Greek 'skhēma' into Latin 'schema' and then into Medieval Latin and Old French forms before entering Middle English as 'scheme' or 'schema', eventually becoming the modern English 'scheme'.

Initially it meant 'form' or 'shape' in Greek; over time it evolved to include 'diagram', 'organized arrangement', and later 'a planned course of action' or 'plot', which are its dominant modern senses.