convulsion

(noun) a sudden uncontrollable attack. Synonyms: paroxysm, fit. Examples: "A paroxysm of giggling." "A fit of coughing." "Convulsions of laughter."

(noun) violent uncontrollable contractions of muscles.

(noun) a violent disturbance. Synonyms: turmoil, upheaval. Example: "The convulsions of the stock market."

(noun) a physical disturbance such as an earthquake or upheaval.