The Collaborative International Dictionary of English v.0.48:

jumbo \jum"bo\ (j[u^]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]

The Collaborative International Dictionary of English v.0.48:

jumbo \jum"bo\ (j[u^]m"b[-o]), n.
   Any object which is a very large example of its class.
   [PJC]

WordNet (r) 3.0 (2006):

jumbo
    adj 1: of great mass; huge and bulky; "a jumbo jet"; "jumbo
           shrimp" [syn: elephantine, gargantuan, giant,
           jumbo]

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



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

JUMBO
       Java Universal Molecular Browser for Objects (XML)