Real Dictionary

laugh
verb: When you laugh, you make a sound with your throat while smiling and show that you are happy or amused. People also sometimes laugh when they feel nervous or are being unfriendly.

laugh in American English
to make the explosive sounds of the voice, and the characteristic movements of the features and body, that express mirth, amusement, ridicule, etc.
intransitive verb: to express mirth, pleasure, derision, or nervousness with an audible, vocal expulsion of air from the lungs that can range from a loud burst of sound to a series of quiet chuckles and is usually accompanied by characteristic facial and bodily movements
transitive verb: to drive, put, bring, etc., by or with laughter

laugh in British English
verb: to express or manifest emotion, esp mirth or amusement, typically by expelling air from the lungs in short bursts to produce an inarticulate voiced noise, with the mouth open