[1] : The Collaborative International Dictionary of English v.0.48

cachinnation \cach`inna"tion\ ka^k`i^nn=a"shu^n, n.
   l. cachinnatio, fr. cachinnare to laugh aloud, cf. gr.
   kacha`zein.
   loud or immoderate laughter; -- often a symptom of hysterical
   or maniacal affections.
   1913 webster

         hideous grimaces . . . attended this unusual
         cachinnation.                            --sir w.
                                                  scott.
   1913 webster

[2] : WordNet (r) 2.0

cachinnation
     n : loud convulsive laughter

Cachinnation >> C Words
Cachinnation, definition of term: Cachinnation
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