'Kěn shū' literally means 'to gnaw books', evoking the image of a person chewing through thick textbooks with focused, persistent effort — much like a rodent gnawing on hard material. The verb 啃 (kěn) implies slow, determined, sometimes laborious action, while 书 (shū) means 'book' or 'study material'. Together, they form an informal, vivid idiom describing intensive, diligent studying — often self-directed and requiring stamina.

This expression is commonly used in student contexts, especially when preparing for exams like the Gaokao or professional certifications. It carries a slightly colloquial, even affectionate tone — suggesting respect for the effort involved, though not necessarily implying enjoyment. While it can hint at rote memorization, it more broadly conveys deep engagement with challenging material over time, rather than passive reading or casual learning.