The word 手淫 is formed by directly combining two conceptual elements: 手 (shǒu), meaning "hand", and 淫 (yín), which in this context carries the meaning of "lewdness" or "excessive/improper sexual activity". The character 手 provides the concrete instrument or method, while 淫 conveys the abstract nature of the act as a sexual transgression or solo indulgence. Together, they create a visually and semantically straightforward compound that literally signifies a "lewd act performed with the hand", forming a euphemistic yet descriptive term for masturbation.