Wiktionary
knife pleat
n. (context sewing English) A type of sharply pressed pleating, especially in a skirt or kilt, in which all of the folds are turned in one direction, with each pleat being three layers of fabric thick.
WordNet
knife pleat
n. a single pleat turned in one direction
Usage examples of "knife pleat".
She lifted a brow and gestured to indicate the knife pleat in Regan's navy trousers, the polished buttons on the double-breasted blazer.