'emaciation' originates from Latin, specifically from Medieval Latin 'emaciatio' (from the verb 'emaciare'), where the prefix 'e-/ex-' meant 'out' and the root 'macies' meant 'thinness'.

'emaciation' changed from the Medieval Latin word 'emaciatio' and was borrowed into English (via learned usage) as the modern English word 'emaciation'.

Initially, it meant 'the process of making thin' or 'being made thin', but over time it came to denote 'extreme thinness, especially due to illness or lack of food'.