'aurelian' originates from Latin, specifically the word 'aurelianus' (from the family/name 'Aurelius'), ultimately from 'aurum' meaning 'gold'.

'aurelianus' in Late Latin passed into medieval/early modern usage (via learned Latin and occasional French/English literary borrowing) and became the English adjective and noun 'aurelian'.

Initially related to the name 'Aurelius' or the idea of 'golden' (from 'aurum'), the word came to mean 'golden' in descriptive contexts and later, by specialized/archaic usage, was used as a noun for someone who collects butterflies.