Something that's jumbo is extra large. Your jumbo television might look funny in your tiny apartment.
Jumbo is an informal adjective that describes anything enormous. You might spy the word on a menu at a seafood restaurant that serves "jumbo shrimp," or hear it when you're boarding a massive "jumbo jet." The word comes from a famous elephant, Jumbo, known for being the largest in captivity in the 1800s, and purchased from the London Zoo by circus owner P.T. Barnum in 1882.