The stuff I feed my dogs is called dog food ...

The container we put my son's toys in is called a toy box ...

"Newsweek" is a magazine about news in the last week ...

I live near a lake called Lake Clear, which is a lake filled with very clear water ...

So why is the tape I use every time I go geocaching but have never used anywhere near a duct (or a duck, for that matter) called duct tape? The name of a thing should reflect its use.