The compound word 牢狱 (láoyù), meaning "prison" or "jail," is formed through the combination of two synonymous characters, each contributing to the overarching concept of confinement. The first character, 牢, originally depicted an enclosure for livestock, evolving to signify a secure, confining prison. The second character, 狱, historically related to lawsuits and disputes, came to denote the physical place of detention resulting from legal judgment. By pairing these two semantically similar morphemes, the word creates a more precise and emphatic term for a penitentiary, leveraging their combined connotations of enforced enclosure and legal punishment to solidify its modern meaning.