I may be, I'll look in a dictionary to find the appropriate translation in my language. Fretting as far as I know it's a temperature based tight assembly type with the use of dilatation (exterior diameter is heated to red, the inner part is freeze and assembly is done easly. When they cold/heat up, they realize a strong pressure between the pieces).
No, that's not it at all. Read the Sheldon Brown link to the Jobst Brandt article on headsets referenced above.