of great mass; huge and bulky; "a jumbo jet"; "jumbo shrimp"
jum'b[=o], n. a colossus.--adj. huge, colossal. [Name of a huge elephant sold in 1882 from the London Zoological Gardens to P. T. Barnum.]
Big clumsy person, animal or thing, esp. (J-) famous elephant in London Zool. Gardens; notably successful person. [?]