Dictionary.net

Any type of variation in the appearance of energy output of the sun. (NASA Thesaurus, 1994)

1. Notional cause of an odd error. "Why did the programsuddenly turn the screen blue?" "Sunspots, I guess."2. Also the cause of bit rot - from the myth that sunspotswill increase cosmic rays, which can flip single bits inmemory. See also phase of the moon.