The word 关闭 is formed by combining two characters, 关 and 闭, which both independently convey the core idea of shutting or closing. 关 originally depicted a bar across a gate, representing the act of barring or shutting, while 闭 depicts a door being bolted or sealed shut. When paired, they create a single, reinforced concept where their meanings overlap and intensify, picturing the complete and secure action of closing something down, like shutting a gate and fastening it. It is a classic example of a compound where two synonyms merge to form a unified, often more emphatic, meaning.