Meaning of A4 in English

A4

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.