The word "嘴脸" is formed by combining the character "嘴", meaning mouth, which is constructed from the mouth radical (口) indicating its category and the phonetic component "觜" suggesting pronunciation, with the character "脸", meaning face, which is constructed from the meat radical (月) indicating its relation to body parts and the phonetic component "佥" guiding its sound; together they create a compound that literally refers to the mouth and face, representing facial features or expression.