the area between the heart and the diaphragm, traditionally considered unreachable by medicine; also used to describe a terminal illness or deep-seated trouble when used in the phrase 病入膏肓 bìng​rù​gāo​huāng

an acupuncture point located on the back, specifically three inches lateral to the lower border of the spinous process of the fourth thoracic vertebra

(literary) the distress or bitter suffering of the common people