pleat

Entry Definition
it is crumpled in pleats
it wrinkles as it moves; it crumples in pleats, bunches up
it is corrugated or pleated
it is formed in shape of small waves (crimped, corrugated, pleated, etc.)
s/he, it crinkles, forms or becomes covered with small folds or ripples, etc.
(cloth, etc.) it is pleated, folded over