A guffaw is a belly laugh: a laugh that bubbles up with good feeling and plenty of volume. At the end of a stressful day of work, it’s good to have some guffaws with your friends.
Guffaw operates just like the word laugh: you can give a guffaw, or you can guffaw. It comes from the Scottish word gawf, which is onomatopoetic, meaning that it’s spelled the way it sounds. Imagine a big happy Scotsman snorting "gawf, gawf, gawf" at the end of a joke, and you’ll know what a guffaw is. Refined ladies and gentlemen don’t guffaw––and are much the worse for it.