Definition of launch party in US English:

launch party

noun

  • A party held to celebrate the launch of a new product or publication.

    ‘tonight was the launch party for their new CD’
    • ‘We had a launch party where we tried to give the records away.’
    • ‘The launch party will begin with a half-hour presentation by the site designers.’
    • ‘I met up with people at the launch party for the free festival group.’
    • ‘To kick things off, he threw a launch party at the Plaza Hotel.’
    • ‘It was at the launch party for this magazine that he met his first wife.’