“Rambunctious” means energetic, noisy, lacking in restraint or discipline, exuberant, boisterous.
According to the Oxford English Dictionary, the word first appeared in 1830 and is primarily a US term. “Rambunctious” is an alteration of “rumbustious” (1777), meaning “unruly, boisterous,” and “boisterous” is probably an alteration of “robustious” (1548), meaning “sturdy, strong,” which in turn comes from “robust.”
The root of these words is the Latin rōbustus, which the OED relates as something “made or consisting of oak, physically strong, powerful, firm, solid, capable of resisting change, durable.”
This energetic word arose in the US in the early 1800s. It’s first recorded in The Boston Transcript, Sept. 1, 1830: “If they are ‘rumbunctious’ at the prospect, they will be ‘rip-roarious’ when they get a taste.”
Riproarious is a great word! The Boston Transcript no doubt thought it meant even more extravagantly uninhibited than rambunctious.
Early on, rambunctious was also spelled “rumbumptious” and “rambumptious.” Rum, of course, will make people bumptious, and rams are born bumptious.