Ivar the Boneless' name has been the subject of curiosity for centuries. What exactly does "boneless" mean? Nowadays, there is only conjecture. Scholars do not agree on a unified interpretation. Despite this, there are three distinct possibilities for Ivar the Boneless' monicker. However there is no way to know for sure. Unless Ivar the Boneless is found in some long lost grave, and positively identified, the mystery and speculation will continue.
Ivar the Boneless may have been disabled. This seems to be the most plausible theory. Perhaps his legs were useless. In this case, a better translation might be Ivar the Legless. There are stories that he was carried on a shield by his warriors. The loss of his legs through battle, birth defect, or accident could have rendered Ivar "boneless."
The Viking's legs are not the only source of interest for scholars researching the nickname. Some believe the king suffered from a form of brittle bone disease. The sources record Ivar's legs "lacked bones." As a result, he needed to be carried into battle. However, he could still wield a sword or bow and earn his reputation as a fierce warrior.
The third major theory has nothing to do with leg defects. Instead, some believe Ivar the Boneless was impotent. In this case, boneless refers to the Viking's inability to produce offspring. It could also refer to erectile dysfunction. In this case, boneless refers to his sexual prowess or lack thereof.
The three major theories cover some sort of disability whether disease, deformity, or dysfunction. There are a few other ideas surrounding the nickname worth mentioning. Some believe Ivar was a midget. This is unlikely, but can not be completely discounted at this time. Another theory ties to his brother nicknamed "Snake-in-the Eye." Could boneless refer to some form of limberness and flexibility like a snake? Lastly, other diseases have been suggested including diabetes.
Viking scholars and other interested parties may never know the meaning of Ivar the Boneless' title. The best guesses surround some sort of disability or inability to procreate. However, there is no way to know for sure. In the end, someone needs to stumble upon Ivar's remains to uncover the truth.