laughing

Concise Oxford English Dictionary © 2008 Oxford University Press:
laugh/lɑːf/

▶verb

• 1 make the sounds and movements that express lively amusement and sometimes also derision.

  ■ (laugh at) ridicule; scorn.

• 2 (laugh something off) dismiss something by treating it in a light-hearted way.

• 3 (be laughing) informal be in a fortunate or successful position.

▶noun

• 1 an act of laughing.

• 2 (a laugh) informal a person or thing that causes laughter.

– phrases
have the last laugh be finally vindicated.
a laugh a minute very funny.
laugh on the other side of one's face (or N. Amer. out of the other side of one's mouth) be discomfited after feeling confident or triumphant.
laugh someone/thing out of court dismiss someone or something with contempt as being obviously ridiculous.
laugh up one's sleeve be secretly or inwardly amused.

– derivatives
laugher noun,
laughing adjective,
laughingly adverb.

– origin OE hlæhhan, hliehhan, of Gmc origin.