'x-ray' originates from German, specifically the word 'X-Strahl,' where 'X' referred to the unknown nature of the radiation and 'Strahl' meant 'ray.'

'X-Strahl' transformed into the English word 'x-ray' and eventually became the modern English term 'x-ray.'

Initially, it meant 'unknown ray,' but over time it evolved into its current meaning of 'a type of radiation used for imaging.'