'non-contentious' originates from the prefix 'non-' meaning 'not' and the word 'contentious' from Latin 'contentiosus', where 'contentio' meant 'strife' or 'dispute'.

'contentiosus' transformed into the Old French word 'contentieux', and eventually became the modern English word 'contentious'. The prefix 'non-' was added to form 'non-contentious'.

Initially, 'contentious' meant 'full of strife', but 'non-contentious' evolved to mean 'not causing strife or disagreement'.