There's some zany animal confusion going on about rabbits. Most think rabbits are rodents, and until 1912, scientists thought so too, however they're not rodents but part of the lagomorph order, which includes hares and pikas. Adding to the confusion, bunnies are called kittens or kits. Mature females are known as does while adult males are called bucks. And here's a real shocker. According to experts, rabbits are most like horses. Yes, you read that right. Horses! Horses and rabbits share many similarities, including their method of digesting food. And rabbits suffer colic and need to have their ever growing teeth floated--just like horses. So a six-pound rabbit is really, you guessed it, like a 1000 plus pound horse. That would be a lot of rabbit! A scary rabbit and perfect fodder for a B movie. Bugs Bunny would have nothing on such a carrot-eating colossus.
As for the word "Bunny," it falls into the same category of cute terms like "kitty" and "doggy"—and has no scientific basis.