交叉的大腿骨图形
Crossbones \Cross"bones`\ (-b[=o]nz`), n. pl. A representation of two of the leg bones or arm bones of a skeleton, laid crosswise, often surmounted with a skull, and serving as a symbol of death. Crossbones, scythes, hourglasses, and other lugubrios emblems of mortality. --Hawthorne.
crossbones n : two crossed bones (or a representation of two crossed bones) used as a symbol danger or death