Definition of rumble-de-thumps in US English:

rumble-de-thumps

noun

Scottish
  • A dish of mashed potato cooked with fat and often also cabbage, onion, etc.

Origin

Early 19th century. From rumble + an arbitrary element -de- + thump.

Pronunciation

rumble-de-thumps

/ˈrʌmb(ə)ldɪˌθʌmps/