'non-combined' originates from the negative prefix 'non-' (from Latin 'non', meaning 'not') attached to 'combined', which derives from Latin 'combinare' ('com-' meaning 'together' + related root meaning 'to join').

'combined' entered English via Old French 'combiner' and Middle English forms from Latin 'combinare'; the modern English adjectival form 'non-combined' is formed by adding the productive prefix 'non-' to the past-participle-based adjective 'combined'.

Initially the parts meant 'not' (non-) and 'joined together' (combined); over time the compound simply denotes the straightforward modern meaning 'not joined or merged'.