Cross folding is characterized by a right angle, unlike the parallel folds found on an accordion fold for example. That is to say, when you unfold your sheet, the lines formed by these two folds form a cross on the paper: so we can call it fold cross. You have probably already encountered this type of folding in medication leaflets or stitched advertising brochures.
"Why cross iron when you can cross words?" (Bélinda Ibrahim)