A character is wearing a cape that is not attached to them directly. Often the result of some magic or technology, though the exact nature needn't be explained.
It should be visually apparent that the cape is not attached to the wearer, otherwise the cape would be visually indistinguishable from a regular cape.
Detached capes may hover anywhere along the body. They are usually near the neck and shoulders, however some may be near the waist or elsewhere (see: post #4053057)