Definition of keynote speaker in US English:

keynote speaker

noun

  • A person who delivers a speech that sets out the central theme of a conference.

    ‘Harry Reid will be the keynote speaker at the convention’
    • ‘The opening keynote speaker drove home the vital importance of changing today's standards of design to promote sustainability.’
    • ‘The director of the Whitney Museum of American Art will be the show's keynote speaker.’
    • ‘He is a keynote speaker at commencement ceremonies at Calvin College.’
    • ‘He will be the keynote speaker at a "peace conference" at the city hall tomorrow.’
    • ‘A keynote speaker at the International Famine Centre detailed how maize was loaded on ships bound for Britain at the height of the great Irish potato famine.’