con ‧ vul ‧ sion /kənˈvʌlʃ ə n/ BrE AmE noun [countable]
1 . a shaking movement of your body that you cannot control, which happens because you are ill SYN seizure :
His temperature was very high and he went into convulsions.
2 . [usually plural] a great change that affects a country:
the 19th-century political convulsions in France
3 . be in convulsions to be laughing a lot