歐亞大陸有兩個古語燈塔。一個是日耳曼語系的立陶宛語，一個是漢語的閩方言。從漢語方言分區的進程看，自有漢語分區以來，閩語即為獨立一區，向無疑義；然而到了1987 年《中國語言地圖集》面世，學者卻仍不免為閩語的適切定義猶豫不決，舉箸難定。閩語界說不予確定，什麼是閩南話勢將無從說起。定義難下出於焦點轉移、模糊。方言作為歷史的產物，作為語言的地域變體，探討方言有必要注視其歷史人文背景及其所處社會環境。孕育閩語的自然環境是三山一海；乘桴浮於海與翻山越嶺而來的是兩種人文現象。由海及山，方言色彩漸次變異。其變化有如湖心、漣漪。論及閩語，宜從湖心開展。湖心就是代表點，傳統地方韻書產地即為湖心所在，而沿海又重於內陸。以此觀之，所謂閩語即「十五音」系統的漢語方言。什麼是閩南話？即閩江、戴雲山以南十五音方言中「魚」讀h-，「錢」讀_⊆tsĩ 的方言。

In theory, dialect sub-grouping is a by-product of linguistic reconstruction and definition of a certain dialect can be drawn from an established tree diagram. In practice, Chinese dialectologists face difficulties when they are asked to give a proper definition for some dialect groups, among them Min is one. If we are focused on the five representative dialects of Min, a common feature soon presents itself: A Min dialect is a Chinese dialect that has 15 consonants in its initial system, as evidenced by local rhyme books compiled at different times during the Qing Dynasty. Min-nan dialect is any Min dialect which renders the character for ＂fish＂ with an aitch initial and the character for ＂money＂ is pronounced as _⊆tsĩ. As is natural, details may vary in the border region or outliers, but they can all be shown to have derived from the two original features.