laugh (v.) Look up laugh at Dictionary.com
late 14c., from Old English (Anglian) hlæhhan, earlier hlihhan, from Proto-Germanic *klakhjan (cognates: Old Norse hlæja, Danish le, Old Frisian hlakkia, Old Saxon hlahhian, Middle Dutch and Dutch lachen, Old High German hlahhan, German lachen, Gothic hlahjan), from PIE *kleg-, of imitative origin (compare Latin cachinnare "to laugh aloud," Sanskrit kakhati "laughs," Old Church Slavonic chochotati "laugh," Lithuanian klageti "to cackle," Greek kakhazein). Originally with a "hard" -gh- sound, as in Scottish loch; the spelling remained after the pronunciation shifted to "-f."
If I coveted nowe to avenge the injuries that you have done me, I myght laughe in my slyve. [John Daus, "Sleidanes Commentaries," 1560]
Related: Laughed; laughing.
laugh (n.) Look up laugh at Dictionary.com
1680s, from laugh (v.). Meaning "a cause of laughter" is from 1895; ironic use (as in that's a laugh) attested from 1930. Laugh track "canned laughter on a TV program" is from 1961.