Pathology. a condition characterized by sudden, brief attacks of muscle weakness sometimes causing the body to fall helplessly, that is usually triggered by strong emotion: often associated with narcolepsy.
Origin of cataplexy
1880–85; < GermanKataplexie < Greekkatáplēxis (with suffix probably by analogy with Apoplexieapoplexy) fixation (of the eyes), equivalent to kataplēk- (variant stem of kataplḗssein to strike down) + -sis-sis
Related formscat·a·plec·tic[kat-uh-plek-tik]/ˌkæt əˈplɛk tɪk/, adjective
"the state of an animal when it is feigning death," 1883, from German kataplexie, from Greek kataplexis "stupefaction, amazement, consternation," from kataplessein "to strike down" (with fear, etc.), from kata- "down" (see cata-) + plessein "to strike, hit," from PIE *plak- (2) "to strike" (see plague (n.)). Related: Cataplectic.