A4 Meaning of A4 in English A4 /ˌeɪ ˈfɔː◂ $ -ˈfɔːr◂/ BrE AmE noun [uncountable] a standard size of paper, used in Europe and Japan. A4 paper measures 210 x 297 ↑ millimetre s ⇨ A3 , A5 Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012