The word "郊外" is formed by combining the character "郊", meaning suburbs or outskirts, which itself integrates the semantic component "阝" (indicating terrain) with the phonetic component "交", and the character "外", meaning outside, historically derived from "夕" (evening) and "卜" (divination) to convey externality, resulting in a compound that literally signifies "outside the suburbs" or the rural area beyond.