Search Result for "cachinnation": 
Wordnet 3.0

NOUN (1)

1. loud convulsive laughter;

The Collaborative International Dictionary of English v.0.48:

Cachinnation \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. [1913 Webster] Hideous grimaces . . . attended this unusual cachinnation. --Sir W. Scott. [1913 Webster]
WordNet (r) 3.0 (2006):

cachinnation n 1: loud convulsive laughter