Another fun fact from one of my favorite authors, Bill Bryson:
You may know that the largest elephant ever kept in captivity was a circus elephant named Jumbo. However, many think that he was named Jumbo because of his size. Actually, the word "Jumbo" got its meaning of "oversize" from the elephant!
Jumbo was named when he was born in 1861, when no one could predict his adult size. He got the name from "mumbo jumbo", which was a West African term for "witch doctor" and later an English term for "gibberish". It was probably just meant to be a silly name for the baby elephant. Little did his namers know that Jumbo would eventually grow to be over 11'7" tall, and PT Barnum would promote him so much that "jumbo" would become synonymous with "huge"!
bonus: In the Disney film Dumbo, Dumbo's mom's name was "Mrs. Jumbo" and she named him "Jumbo, Jr". Due to his huge ears, he got the nickname "Dumbo". I can only assume that these names all were inspired by the original Jumbo himself. That elephant ended up being pretty influential!