The dog bit down on the bone and refused to let go no matter what.
Tips
usage
松口 has both literal (release from mouth) and figurative (relent, concede) meanings. The figurative sense is far more common in modern usage — especially in negotiation, debate, or family disagreements.
memory
松 means loose/relax, 口 means mouth. To relax the mouth = to let go of your position. A stubborn person keeps their mouth tight (不松口).
