flat paper; flat sheet
Refers to paper or sheets that are flat, as opposed to rolled or folded. Often used in contexts like printing, packaging, or stationery.
This printer can only use flat paper.
Stack flat sheets of cardboard in the warehouse.
Compound of 平 (ひら, 'flat') and 判 (ばん, 'size' or 'format'), referring to a flat format of paper or sheet material.