căchinnātĭo, ōnis, f. [cachinno],
a violent laughing , immoderate laughter : sine ullā suspitione nimiae suspitionis, Auct. Her. 3, 14, 25: ut si ridere concessum sit, vituperetur tamen cachinnatio, Cic. Tusc. 4, 31, 66.
cachinnātiō ōnis,f cachinno, violent laughter, excessive laughter . ...
An Elementary Latin Dictionary