box pleat

English Thesaurus

1. a flat double pleat made by folding under the fabric on either side of it (noun.artifact)

hypernym	:	plait, pleat,
definition	:	any of various types of fold formed by doubling fabric back upon itself and then pressing or stitching into shape (noun.artifact)

part meronym	:	skirt,
definition	:	a garment hanging from the waist; worn mainly by girls and women (noun.artifact)