Cloaking is the act of shielding one's appearance.
Stealth in spaceEdit
Stealth in space is considered impossible. It is much easier to hide within an area that obscures radio or infrared signals than it is to actually become completely invisible.
The biggest problem for craft in space is heat. Most would assume that you can simply radiate excessive heat out into space, which is cold, but cooling-by-radiation is in truth rather inefficient. Plus, due to the laws of thermodynamics and conservation of energy, any attempt at transferring heat energy will necessarily produce even more heat.
A ship big enough to afford carrying extra expendable resources can transfer excess heat into coolant substance of sorts and then jettison it — but obviously that substance will glow even brighter, as it's warmer. Instead of jettisoning it, the ship could also store the excess heat in an isolated heat “sink” of some kind or another, but this has a finite time limit. Eventually your ship will have to “drop” heat somewhere.
Why is this a problem? Simply because that dropping is detectable from a very long way off to anyone with infrared technology. This means that a typical spaceship with lots of machinery and electronics is going to glow like a fire in the sky unless extraordinary measures are taken to contain its emissions. The complications rise rapidly should you wish humans to actually inhabit this ship, since you need a tremendous amount of heat-generating systems to keep them alive, on top of having to fill your ship with reasonably warm gas such as oxygen.
Wanting this stealth ship to move creates even more problems. All propulsion methods generate lots of heat/energy that will radiate in a cone out into space behind you—easily traceable. On top of all the problems involving infrared detection, there is also the rest of the EM spectrum to be concerned about. If you transmit a radio signal, that can be detected. If you wish to use radar or other active sensors to be sure you don't fly into something or find an enemy, that can be detected. Stealth necessarily invokes a certain measure of "flying blind" to not give yourself away. As such you can only use passive sensors, though it should be noted this isn't as dangerous as you might think, simply due to the fact that space is mostly empty.
The opposing force that isn't trying to hide is completely free to use their active sensors, so you need to block/confuse all their active sensors as well. Modern submarines operate under similar ideas and have for years, but in space, this is far more complicated. Garden planet environments tend to limit ranges and provide lots of interference compared to the vacuum of space.
Perhaps, and this is worst of all, someone with a good enough telescope can just plain spot you visually. Many modern satellites are visible from the ground on a clear night with just the naked eye as little moving points of light. Being visible to the eye can be dealt with if the concept involves an Invisibility Cloak, but expanding it to spaceship size will not eliminate its own problems. The whole point of an Invisibility Cloak is to deflect EM radiation away from your ship, meaning your passive sensors won't be receiving anything, be they your sensor beams, radio telemetry from your non-invisible pals, or even just ambient radiation from stars. Long story short, if the Invisibility Cloak is working right and/or according to the laws of physics, he can't see you, but you can't see anything.