I find this word being used, mainly by authors and reporters of Indian origin, increasingly in recent times. Dictionaries available to me neither give its origin nor the first appearance. Can somebody help?
First appearance, according to the OED3, is 1830. It’s primarily a US term.
Rambunctious is an alteration of rumbustious (a1777), “unruly, boisterous,” which is probably an alteration of robustious (1548), meaning “sturdy, strong,” which in turn comes from robust.