Corrugated board,

Definition of Corrugated board:

1. Packaging material formed by gluing one or more fluted sheets of paperboard (corrugating medium) to one or more flat sheets (called facings) of linerboard. Its comes in four common types: (1) Single face: one fluted sheet glued to one facing (total two sheets). (2) Single wall: one fluted sheet sandwiched between two facings (total three sheets); also called double face or single ply. (3) Double wall: one single-face glued to one single wall so that two fluted sheets are alternatively sandwiched between three flat sheets (total five sheets); also called double cushion or double ply. (4) Triple wall: two single-face glued to one single wall so that three fluted sheets are alternatively sandwiched between four flat sheets (total seven sheets); also called triple ply. See also flute.