'isomer' originates from Greek, specifically the word 'isomerēs,' where 'iso-' meant 'equal' and 'meros' meant 'part.'

'isomerēs' transformed into the French word 'isomère,' and eventually became the modern English word 'isomer' through scientific Latin.

Initially, it meant 'having equal parts,' but over time it evolved into its current meaning of 'compounds with the same formula but different structures.'