\Cach`in*na"tion\ (k[a^]k`[i^]n*n[=a]"sh[u^]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.

      Hideous grimaces . . . attended this unusual
      cachinnation.                            --Sir W.
                                               Scott.