As a Noun: 1. The sounds people make by which they show that they are happy or amused or the action of makings such sounds. English = laughter. 2. Amusement which you express by laughing. Literary English = mirth. 3. Something that is funny and makes you want to laugh; a style or type of theatre that is funny. English = humour; comedy. 4. [Especially with stress] great amusement and laughter. English = hilarity. As a Verb or Adjective: 1. To make the sound by which people show that they are happy or amused. English = laugh. 2. To be happy and joyful and to show it in your behaviour. English = (be) cheerful. 3. To be funny and make you want to laugh; [especially with stress] to be extremely funny and to make you laugh a lot. English = (be) humorous; (be) hilarious. 4. [Especially with stress] to laugh very loudly and with great energy. Idiomatic English = roar with laughter, (be) in the aisles laughing.