Source : Webster's Revised Unabridged Dictionary (1913)

Guffaw \Guf*faw"\, n.
   A loud burst of laughter; a horse laugh. ``A hearty low
   guffaw.'' --Carlyle.

Source : WordNet®

guffaw
     n : a burst of deep loud hearty laughter [syn: {belly laugh}]
     v : laugh boisterously [syn: {laugh loudly}]