'deterioration' originates from Latin, specifically the word 'deteriorare' (from 'deterior'), where 'deterior' meant 'worse' and the suffix '-ation' indicated an action or process.

'deterioration' changed from Late Latin 'deterioratio' (and Medieval Latin/French forms) and eventually became the modern English word 'deterioration'.

Initially, it meant 'a process of becoming worse', and over time it has retained that core meaning as the modern sense of 'deterioration'.