Definition of A4 in English:

A4

noun

mass noun
  • 1A standard European size of paper, 297 × 210 mm.

    as modifier ‘an A4 page’
    • ‘Posters are to be A4 in size with the name clearly written on the front and the address on the back.’
    • ‘The questionnaire, on one side of A4 paper, asks people to express their opinions on what matters to them about the village.’
    1. 1.1 A4 paper.
      ‘several sheets of A4’
      • ‘The CV is important because you can outline skills and experience far easier on A4 than you can on a business card!’
      • ‘I've somehow got through a mountain of paperwork (suffice it to say that I have used an entire 500 sheet pack of A4).’