any of several vegetables (Brassica pekinensis and B. chinensis) of the crucifer family, having long, narrow leaves in loose, cylindrical heads and tasting somewhat like cabbage
See Chinese cabbage in American Heritage Dictionary 4
noun
A plant (Brassica rapa subsp. pekinensis) of the mustard family, having an elongated head of overlapping, crinkled, broad-stalked leaves and eaten as a vegetable in eastern Asian cuisine. Also called celery cabbage, napa, pe-tsai.