'non-adjustable' originates from the prefix 'non-' meaning 'not' and the word 'adjustable', which comes from the Latin 'ad-' meaning 'toward' and 'justus' meaning 'right' or 'proper'.

'adjustable' evolved from the Old French word 'ajuster', which was derived from the Latin 'adjuxtare'. The prefix 'non-' was added in modern English to indicate the opposite meaning.

Initially, 'adjustable' meant 'capable of being made right or proper', and with the prefix 'non-', it evolved to mean 'not capable of being adjusted'.