'azureous' originates from English, formed from the adjective 'azure' plus the suffix '-ous'; 'azure' itself comes from Old French 'azur', ultimately from Arabic 'al-lazaward' (lazaward) meaning 'lapis lazuli'.

'al-lazaward' (Arabic) passed into Old French as 'azur', then into Middle English as 'azure'; the modern English adjective 'azureous' was formed by adding the adjectival suffix '-ous' to 'azure'.

Initially related to the gemstone lapis lazuli ('a deep blue stone'), the term shifted to denote the blue color itself and now means 'sky-blue' or 'azure-like' in modern usage.