A bowling ball with a handle?
Yes, that is frequently how both steel and cast iron kettlebells are described.
An old strength endurance tool from Russia, the original word "girya" indicated a counter weight for shipyard scales. The person who moved the girya was known as the "giryvek" or "kettlebell man."
This all makes since to look at the things. They are bottom-heavy, like a rounded bucket full of metal with a built-in handle for ease of maneuvering.
Once a person as seen one the shape is unmistakable, but the name is often mistaken.
As a trainer of kettlebells I've heard everything, kettle balls, cow bells, cow balls.... it's a little out of control.
In the early days of my kb lifting practice I even asked "do they ring..?" Well, some of them actually do have loose steel inside which creates a chiming sound when in action.
So to de-mystify the name for my friends and fellow lifters, I looked it up on good old Wikipedia and found the original us of the word "bell".
It all starts with dumb bell. According to my Wikipedia source, and the Oxford Dictionaries online, the solid clacker of a church bell was in fact used for strength training back in the 18th century. As it was the silent part of the instrument, the word "dumb"discribed it as being soundless.
This does not explain why weightlifters carried over the suffix with "barbell" other than the convenience of word recognition. Infact, many "old time" strongmen trained with a variety of objects, both symetrical and asymetrical, farm tools, mechanical parts, some even resembling train axles. A main characteristic of these object is that they are made of metal. This makes them very consistent, which is my favorite feature of my training tool of choice, the kettlebell.