The word 监禁 is formed by combining two characters, each contributing a core meaning to create a new, compounded concept. 监 (jiān) originally depicts a person looking into a vessel of water, evoking the idea of overseeing, watching, or surveillance from a high vantage point, like a prison tower. 禁 (jìn) conveys prohibition, restraint, or a forbidden area. Their union merges the notion of "watchful surveillance" with that of "enforced restraint", crystallizing into the single concept of "imprisonment" or "incarceration", the state of being confined under guard.