A3

A3 UK [ˌeɪ ˈθriː] US [ˌeɪ ˈθri] noun [uncountable]

a large size of paper about 16.5 inches or 420 millimetres wide and 11.5 inches or 297 millimetres long

Thesaurus: types and forms of paper_hyponym

* * *

n. [mass noun] a standard European size of paper, 420 × 297 mm

[as modifier] A3 posters

■ paper of this size

a prospectus printed on A3