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

'proteios' transformed into the French word 'protéine', and eventually became the modern English word 'protein', from which 'proteinous' is derived.

Initially, 'proteinous' meant 'relating to primary substances', but over time it evolved into its current meaning of 'relating to or containing protein'.