A random or sudden outburst (of activity). / An explosive event during a volcanic eruption. / A sudden recurrence of a disease, such as a seizure or a coughing fit.

plural of paroxysm

Of, pertaining to, causing or accompanied by paroxysms.

In a paroxysmal manner.

Relating to paroxysms.

An inability to walk based on trembling and sudden stiffening of the legs.

A disease of humans characterized by sudden hemoglobinuria, typically after exposure to cold temperatures.