'azulejo' originates from Arabic, specifically the word 'al-zulayj', where 'al-' meant 'the' and 'zulayj' referred to a 'polished' or 'glazed' small tile (literally 'little polished stone').

'azulejo' changed from the Arabic term 'al-zulayj' into medieval Iberian forms and was adopted into Spanish and Portuguese as 'azulejo', eventually entering English as the loanword 'azulejo/azulejos'.

Initially, it referred to a 'little polished stone' or polished/glazed piece used decoratively; over time it evolved to mean specifically a tin-glazed ceramic tile and, by extension, surfaces or panels made of such tiles.