We don't have synonyms for gatefolds yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are gatefold.
(n) :
A document folding method that uses two parallel folds to create six panels; the left and right panels are half the width of the center panels and fold inward to meet in the middle without overlapping.
(n) :
A document folding method that uses two parallel folds to create six panels; the left and right panels are half the width of the center panels and fold inward to meet in the middle without overlapping.