'non-Roman' is formed from the prefix 'non-' (from Latin 'non', meaning 'not') combined with 'Roman' (from Latin 'Romanus', meaning 'of Rome').

'Roman' comes from Latin 'Romanus' which passed into Old French and Middle English as 'roman/romain' and later 'Roman'; the productive English prefix 'non-' (from Latin 'non') has been used in compounds since Middle English and more commonly in Modern English to negate adjectives and nouns, giving rise to compounds like 'non-Roman'.

Initially the components meant 'not' and 'of Rome' respectively; the compound has retained the core sense of 'not Roman' while extending to modern uses such as describing scripts ('not using the Roman/Latin alphabet') and broader cultural or institutional non-affiliation.