While it is quite common to study dialect etymology by comparing cognates with regular sound correspondences, we found that isomorphic words, e.g. synonyms with parallel morphological structure in related dialects, could be of great assistance in a different way. Thus, both cognates and isomorphic words are helpful in etymological studies. In this paper, three sets of isomorphic words from the Southern Min dialect are discussed: tsiN2 in1 lau7 pe7(inherited from one’s father 遺傳自他 父親)、si7 tua7 laN5(parents 父母親)、kç1 tsia)5(to coax 婉轉勸誘人做某 事). Through the comparison of parallel morphological structures, the core etymons of these sets could be identified successfully as 踵(tsiN2), 氏(si7), and 成 (tsia)5). Parallel morphological structures are found everywhere when comparing Southern Chinese dialects to their northern counterparts. Hence, the comparative study of isomorphic words detailed in this paper present a substantial contribution to the field of historical linguistics.