Kinktionary
More like guidelines and a lot less like definitions.
Chastity Cage
Also known as a "cock cage", sometimes part of a Chastity Belt, but also worn on it's own is a chastity device for people with a penis. Generally made in the shape of a flaccid penis it surrounds the penis and is generally locked into place using a locking mechanism so the wearer cannot easily take the device off.
The main connected kink is chastity but there are more ways of playing with this kind of device. Often people will also play with Humiliation and/or denial of orgasms (as part of Orgasm play) as the small size of the cage may cause discomfort when arousal happens for the wearer. As the person is locked in it can also be used as a method of discipline. In some cases of cuckolding the cuck will wear a cage to take away their own sexual agency while the partner is engaging in sexual acts.
It can be made out of different rigid materials, however metal and plastic are the most common variants. Some use wire and have a cage like appearance where as others use a full cover shell or case that surrounds the penis. As the cage is often intended to be worn over time it is often equipped to allow the wearer to urinate while wearing the device and materials that are easily cleanable are usually preferred.