Wu Collection, Lower Volume Radical: Stone (shí) Lei Kangxi strokes: 20 Page 838, Entry 21 According to the Collection of Rhymes (Jiyun), pronounced lei. Lei kong refers to a small cave or hole. Another interpretation refers to a small mound of earth. Zhuangzi, Autumn Floods chapter (Qiushui pian): The small holes in the great marsh. Annotation: Lei kong, small cave or hole. Also, Sima Xiangru, Rhapsody on the Shanglin Park (Shanglin fu): Hills and voids, mounds and pits.