Also known as: 透明
An object other than clothing that actually, physically allows some amount of light to pass through it. If a normally opaque object such as a wooden desk is rendered partly invisible by artistic fiat, that's X-Ray.
If some article of clothing is transparent, use See-Through Clothes instead. If a person seems to be disappearing, Fading may be appropriate as well; for a character's skin that's transparent, see See-Through Body.