'unglazed' originates from the prefix 'un-' meaning 'not' and the word 'glazed' from Middle English 'glasen', which meant 'to fit with glass'.

'glasen' transformed into the modern English word 'glaze', and with the addition of the prefix 'un-', it became 'unglazed'.

Initially, 'glaze' meant 'to fit with glass', but 'unglazed' evolved to mean 'not covered with a glossy surface'.