The word 深入 is formed by combining two characters: 深 (shēn), meaning "deep", and 入 (rù), meaning "to enter". It is a conceptual fusion where the action of "entering" is directed into a state or realm of "depth", creating a single idea of "to go deep into" or "to penetrate thoroughly". This formation visually and notionally suggests a movement from the surface into a profound core, extending metaphorically from physical spaces to abstract investigations.