Convulsion

Part of speech: noun (n.)

1. An unnatural, violent, and unvoluntary contraction of the muscular parts of an animal body.

2. Any violent and irregular motion or agitation; a violent shaking; a tumult; a commotion. Those two massy pillars, With horrible convulsion, to and fro He tugged, he shook, till down they came. Milton. Times of violence and convulsion. Ames.

Synonyms: Agitation; commotion; tumult; disturbance.