fanfold
Having the shape of fan or concertina, with a row of sheets alternately folded…Having the shape of fan or concertina, with a row of sheets alternately folded backwards and forwards.
Dictionary text adapted from Wiktionary (Wiktionary contributors, CC BY-SA 4.0) and Open English WordNet / Princeton WordNet (CC BY 4.0, WordNet License); shared under CC BY-SA 4.0. Example sentences and recordings are credited where they appear.