APA Dictionary of Psychology

n. a sudden loss of muscle tone that may be localized, causing (for example) loss of grasp or head nodding, or generalized, resulting in collapse of the entire body. It is a temporary condition usually precipitated by an extreme emotional stimulus (e.g., an uncontrollable fit of laughter; overwhelming anxiety, excitement, or anger). See narcolepsy; narcolepsy–cataplexy syndrome. —cataplectic adj.