Typologically, English, Chinese and Korean belong to three different types of language. English is inflectional, Chinese is isolating and Korean is agglutinative. Therefore, words of perception in these three languages show some different semantic features. But due to similar physical features and physiological phenomenon, people speaking English, Chinese or Korean language use the same word of perception to express the same meaning or feeling. This paper makes a comparative case study of mouth, 嘴/口 and입, which have rich polysemous features. Their meanings are extended from “the part of human body” to the concrete “entrance” or “person” and then to the abstract “speech act” or “way of speaking”. The meaning extension shows semantic symmetry and asymmetry both interlingually and intralingually in the expressions not only with mouth, 嘴/口 and입 and other words of perception in three languages.