a recreation room, especially one for children, as in a house.
Origin of rumpus room
An Americanism dating back to 1935–40
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for rumpus room
US, Canadian and NZ a room used for noisy activities, such as parties or children's games
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012