extravagant: [14] An extravagant person is literally one who ‘wanders out of’ the proper course. The word comes from the present participle of medieval Latin extrāvagārī, a compound formed from the prefix extrā- ‘outside’ and vagārī ‘wander’ (source of English vagabond, vagary, and vagrant), which seems originally to have been used adjectivally with reference to certain uncodified or ‘stray’ papal decrees. This was the word’s original application in English, and the present-day meanings ‘wildly excessive’ and ‘spending too lavishly’ did not really establish themselves before the early 18th century. => vagabond, vagary, vagrant[extravagant etymology, extravagant origin, 英语词源]