a shape having one or more sharp angles

fold into pleats

any of various types of fold formed by doubling fabric back upon itself and then pressing or stitching into shape

a sharp bend in a line produced when a line having a loop is pulled tight

an irregular fold in an otherwise even surface (as in cloth)

a continuous parallel folding in an accordion-like fashion, that is with folds alternatively made to the front and back in zig-zag folds.