一般而言，同源詞在方言間會呈現語音的規則對應關係。但是除了這種規律性的音變外，語言中也會有個別語詞因特殊原因而有不規則的變化。例如音字脫節的語詞，在欠缺語義規範或補充的情況下，詞素語義模糊，語音容易「走樣」，並導致語詞發生變化。 「吳郭魚」在臺灣閩南語有「南洋鯽仔」、「南文鯽仔」、「南民鯽仔」等說法，「胳肢窩」在臺灣閩南語有「胳下空」、「胳下豅」、「過耳空」等說法，說法紛歧的原因正在於詞素語義模糊，導致語詞發生變化。本文以之為例，考其本字，明其流變。

It is well known that cognates correspond regularly among dialects. Yet irregularities exist. Especially when mismatching in sound-meaning correlation of a word occurs, unpredictable varieties would be created. In this paper, words for “Mouthbreeder” and “Armpit” of Southern Min are examined as examples of the mismatched varieties. The development of these words as well as some related issues are further discussed.