'proteinaceous' originates from the word 'protein', which comes from the Greek word 'prōteios', meaning 'primary' or 'of first importance'.

'protein' was derived from the Greek word 'prōteios', which was adapted into the French word 'protéine', and eventually became the modern English word 'protein'. The suffix '-aceous' was added to form 'proteinaceous'.

Initially, it meant 'relating to protein', and this meaning has largely remained the same in modern usage.