IPA: //ˈpær.ək.sɪ.zəm//
KK: /ˈpærəksɪzəm/
A sudden and intense outburst of emotion, action, or symptoms, often occurring unexpectedly.
She experienced a paroxysm of joy when she heard the good news.
Paroxysm is formed from "para-" (meaning beside or alongside) and "oxys" (meaning sharp or acute) from Greek. The word originally described a sharp or acute attack or sudden outburst, often in a medical or emotional context.
Think of a sudden 'sharp' ('oxys') attack or outburst that comes 'beside' ('para-') the usual state, helping you remember that a paroxysm is a sudden, intense episode.