convulsion

noun
1
a sudden shaking movement of the body that cannot be controlled
تشنج, لرزش ناگهانی
synonym fit
2
a sudden important change that happens to a country or an organization
تغییر ناگهانی, دگرگونی ناگهانی, تحول شدید
political convulsions threatening the stability of new democracies
synonym upheaval