Invisible
An invisible creature is impossible to see without the aid of psionics or some extrasensory ability. They cannot be seen.
The creature might still be detected by the noise they make, the tracks they leave behind, their heat/psionic signature, etc, unless the ability by which they became Invisible also addresses them.
Attack rolls and skill checks against the creature have disadvantage, and the creature’s attack rolls and skill checks against others in a strife have advantage.
