[1] : The Collaborative International Dictionary of English v.0.48

jumbo \jum"bo\ ju^m"b-o, a. from the name jumbo, given to
   a very large elephant exhibited as part of p. t. barnum's
   circus in 1882.
   very large.
   pjc

[2] : The Collaborative International Dictionary of English v.0.48

jumbo \jum"bo\ ju^m"b-o, n.
   any object which is a very large example of its class.
   pjc

[3] : WordNet (r) 2.0

jumbo
     adj : of great mass; huge and bulky; "a jumbo jet"; "jumbo shrimp"
           syn: elephantine, gargantuan, giant
see also:
elephantine gargantuan giant 

[4] : Moby Thesaurus II by Grady Ward, 1.0

45 moby thesaurus words for "jumbo":
   atlantean, brobdingnagian, cyclopean, gargantuan, herculean,
   homeric, abysmal, astronomic, colossal, cyclopean, dinosaur,
   elephant, elephantine, enormous, epic, giant, giantlike, gigantic,
   heroic, hippo, hippopotamus, huge, hulk, humongous, immense,
   infinite, leviathan, mammoth, mastodon, mighty, monster, monstrous,
   monumental, mountainous, oversized, prodigious, profound,
   stupendous, thumper, titanic, towering, tremendous, vast, whale,
   whopper

[5] : Virtual Entity of Relevant Acronyms (Version 1.9, June 2002)

jumbo
     java universal molecular browser for objects xml
     
     

Jumbo >> J Words
Jumbo, definition of term: Jumbo
jumbo_pag1.html

Mumbo Jumbo >> M Words
Mumbo Jumbo, definition of term: Mumbo Jumbo
mumbo+jumbo_pag1.html