A pleat in a piece of clothing is a permanent fold that is made in the cloth by folding one part over the other and sewing across the top end of the fold. a flat narrow fold in a skirt, a pair of trousers, a dress etc (plait)
A fold in the fabric of a garment, as a part of the design of the garment, with the purpose of adding controlled fullness or taking up excess fabric. There are many types of pleats, differing in their construction and appearance