'non-sustainable' originates from the prefix 'non-' meaning 'not' and the word 'sustainable', which comes from Latin 'sustinere', where 'sub-' meant 'up from below' and 'tenere' meant 'to hold'.

'sustinere' transformed into the Old French word 'soustenir', and eventually became the modern English word 'sustain' through Middle English.

Initially, 'sustinere' meant 'to hold up or support', but over time it evolved into its current meaning of 'able to be maintained'.