cachinnate

intr.v., -nat·ed, -nat·ing, -nates.
To laugh hard, loudly, or convulsively; guffaw.

[Latin cachinnāre, cachinnāt-, of imitative origin.]

cachinnation cach'in·na'tion n.
cachinnator cach'in·na'tor n.

verb

To express amusement, mirth, or scorn by smiling and emitting loud, inarticulate sounds: cackle, guffaw, laugh. Informal heehaw. Idioms: die laughing, laugh one's head off, roll in the aisles, split one's sides. See laughter, sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.

to laugh loudly or immoderately

IN BRIEF: v. - Laugh loudly and in an unrestrained way.

Tutor's tip: This word was used in the 2006 Scripps National Spelling Bee finals.