n. A violent and involuntary contraction of the muscular parts of an animal body, with alternate relaxation; a fit.n. Any violent and irregular motion; turmoil; tumult; commotion.n. Specifically, in geology, a sudden and violent disturbance and change of position of the strata; a geological event taking place rapidly and at one impulse, instead of slowly and by repeated efforts: nearly the same as catastrophe or cataclysm. Violent voluntary muscular effort.n. Same as laryngismus stridulus.