'azurous' originates from the English word 'azure' combined with the adjectival suffix '-ous' (from Latin '-osus'), where 'azure' in English ultimately comes from Old French 'azur' (meaning 'lapis lazuli, blue').

'azurous' was formed in Modern English by adding the productive suffix '-ous' to 'azure'. The English 'azure' itself passed from Old French 'azur', which came via Medieval Latin and Arabic 'al-lazaward' from Persian 'lajvard' (the name for lapis lazuli).

Initially associated specifically with the blue of lapis lazuli ('lapis-blue'), the sense broadened in English to mean 'sky-blue' or a bright blue color, which is the current general meaning of 'azurous'.