Default has a pretty loose definition, but what will most likely happen is some kind of debt restructuring (which people will interpret as a default), e.g. exte

Default has a pretty loose definition, but what will most likely happen is some kind of debt restructuring (which people will interpret as a default), e.g. extending the maturity on bonds, writing off some parts of the debt, paying out a lower coupon rate, etc. Basically, german and french banks (who hold a big chunk of the debt) will lose a pile of cash.