A lot vs. Alot: 9 Grammatical Pitfalls
1764, of unknown origin, "prob. a fanciful formation" [OED], possibly an alteration of robustious "boisterous, noisy" (1540s; see robust). First record of rumpus room "play room for children in a family home" is from 1938.
A disturbance; uproar; ruckus
[1764+; origin unknown]