The word "服用" is formed by combining two characters, each contributing a core idea to create a new, unified concept. The first character, "服", carries the sense of submitting to or complying with something, often implying an internal acceptance. The second character, "用", means to use or employ. When fused, the concept evolves beyond simple "use" to specifically mean the act of taking something (like medicine or a supplement) into one's body, thereby submitting to its effects, a consumption that is both physical and voluntary.