extravagant (adj.)
late 14c., from Medieval Latin extravagantem, originally a word in Canon Law for uncodified papal decrees, present participle of extravagari "wander outside or beyond," from Latin extra "outside of" (see extra-) + vagari "wander, roam" (see vague). Extended sense of "excessive, extreme" first recorded 1590s; that of "wasteful, lavish" 1711. Related: Extravagantly.