'noninfectious' originates from the prefix 'non-' meaning 'not' and the word 'infectious' which comes from Latin 'infectiosus', where 'in-' meant 'into' and 'facere' meant 'to make'.

'infectiosus' transformed into the Old French word 'infectieux', and eventually became the modern English word 'infectious'. The prefix 'non-' was added to form 'noninfectious'.

Initially, 'infectious' meant 'capable of causing infection', and with the addition of 'non-', it evolved to mean 'not capable of causing infection'.