Having skin that is significantly lighter in tone than the usual Caucasian/Asian skintone, or skin which appears "bleached," lacking in color. For characters with completely white skin, use white skin.
Pale skin, in most cultures, is associated with nobility since they did not spend a lot of time outside and did not get the tanned skin the commoners have.
A good example of a character usually drawn with pale skin is Ayanami Rei.