1) a person born with a certain shade of lighter hair; no correlation to high or low intelligence.
2) a person born with dark hair but who for some reason decided to dye it blonde; very strong correlation to low intelligence.
Notice that the dumb blonde myth is dictinctly American.
Needless to say it fails to hold water somewhere like Scandinavia, the people of which are noted for their brooding, introspective nature. Somehow, the majority-blonde population there have built some of the most progressive and successful nations in the modern world.