The idiom kěn yìng gǔtou literally means 'to gnaw on hard bones'—a vivid image drawn from how dogs or other animals struggle to chew tough, unyielding bones. Figuratively, it refers to tackling an especially difficult, stubborn, or long-standing problem that resists easy solutions—such as deep-rooted social issues, complex technical challenges, or entrenched bureaucratic obstacles.

This expression is commonly used in formal and semi-formal contexts, especially in political, managerial, or journalistic discourse, to describe determined, persistent efforts to resolve thorny issues. The four characters work together: kěn (gnaw) implies sustained, effortful action; yìng (hard) signals resistance or difficulty; gǔtou (bone) symbolizes something solid, structural, and deeply embedded—not superficial or easily removed.