'Kěn gǔtou' literally means 'to gnaw bones' — a vivid image drawn from how dogs or other animals chew stubborn, tough bones. The verb 啃 (kěn) means 'to gnaw' or 'to bite persistently,' while 骨头 (gǔtou) means 'bone.' Together, the phrase evokes effort, persistence, and overcoming resistance.

In modern figurative usage, 'kěn gǔtou' is commonly used to describe tackling a difficult, time-consuming, or intellectually demanding task — like solving a complex math proof, debugging tricky code, or negotiating a tough contract. It emphasizes slow, steady, determined effort rather than quick success. Though rooted in an animal behavior, it’s now almost exclusively metaphorical in everyday speech and carries a slightly informal, conversational tone. It’s often used with subjects like 'we,' 'the team,' or 'he' and frequently appears with aspect particles like 了 or 着 to indicate completion or ongoing effort.