Content: 1. The content contained in the object. 2. The essence or meaning of something. 3. Philosophical terminology. Refers to the sum of internal factors of things. As opposed to "form". There is nothing in the world without intangible content and intangible form. Content determines form, and form depends on content and changes with the development of content. The form reacts on the content, affects the content, and can also play a powerful role in promoting the development of the content under certain conditions. Content and form are dialectical unity.

Cavity: 1 holes in objects, such as trachoma on castings and holes formed in the lungs of tuberculosis patients. Empty 2 [k ū ngdò ng] has no content or the content is not practical: ~ nothing ~ preaching.