1. （情绪的）突然爆发
A paroxysm of emotion is a sudden, very strong occurrence of it.

2. （咳嗽、大笑或剧痛引起的）身体震颤；阵发
A paroxysm is a series of sudden, violent, uncontrollable movements that your body makes because you are coughing, laughing, or in great pain.

1. a sudden uncontrollable attack

e.g. a paroxysm of giggling
a fit of coughing
convulsions of laughter

Synonym: fitconvulsion