'unsystematic' originates from the prefix 'un-' meaning 'not' and the word 'systematic', which comes from the Greek word 'systēmatikos', where 'systēma' meant 'organized whole'.

'systematic' changed from the Greek word 'systēmatikos' and eventually became the modern English word 'systematic'. The prefix 'un-' was added to form 'unsystematic'.

Initially, 'systematic' meant 'pertaining to a system', and 'unsystematic' evolved to mean 'not pertaining to a system'.