'amateurish' originates from French, specifically the word 'amateur,' where 'amateur' meant 'lover of.' 'Treat' originates from Old French, specifically the word 'traitier,' where 'traitier' meant 'to handle or deal with.'

'amateur' changed from the French word 'amateur' and eventually became the modern English word 'amateurish.' 'Traitier' transformed into the English word 'treat' through Middle English.

Initially, 'amateur' meant 'lover of,' but over time it evolved into its current meaning of 'non-professional.' 'Treat' initially meant 'to handle or deal with,' and this meaning has largely remained the same in modern usage.