瓶胆 píngdǎn thermos liner Origin Definitions Defs Strokes Stroke Words Sentences Sents 瓶 píng noun bottle (bound form) bottle; vase; flask; pitcher; any container with a narrow neck and a large belly胆 膽 dǎn liner The inner part of an object used for holding air or water, such as the bladder of a ball or the glass lining of a thermos flask.