「之言」一直被視為探求語源的訓話術語，然而經由本文對鄭玄《三禮注》「之言」術語所作的分析發現：《周禮注》沿襲傳統用法，以推源為主，偶或釋義；《禮記注》已漸轉化，推源及釋義並用；其後至《毛詩箋》則轉以釋義為主。可見鄭氏訓話由兼具語源學推源及訓話學釋義的雙重觀念，逐漸趨向以訓話學釋義的觀念為主。鄭氏「之言」涵義之演變，對其術語的發展具承先啟後之影響。蓋自《孟子》首開以「之言」正名之例，漢代董仲舒進而將正名主義的聲訓帶入顛峰，今文學與識緯聲訓蠢出；《說文》及《釋名》等字典類專著，使聲訓逐漸走向探源的純語源學方向;鄭玄《注》、《筆》則在日趨訓話學釋義的觀念下，漸次將「之言」、聲訓轉化為釋義為主，並成為後世訓話學的主流。

The word zhi-yan has been regarded as a scholium term to indicate the origin of a Chinese character, but this study makes a new discovery after analyzing the zhi-yan in Zheng Xuan's Annotations on the Three Rites. In the Annotations on the Rites of Zhou, Zheng follows the traditional method of using it mostly to trace word origins and occasionally to explain word meanings. In the Annotations on the Book of Rites, it is equally used for word origins and word meanings; in the Annotations on the Mao Poetry, it is mainly used to explain word meanings. Clearly, Zheng Xuan first uses zhi-yan etymologically but in the end explanatorily.Zheng Xuan's zhi-yan is a turning point in the development of Chinese terminology. The term is firstly used to rectify word meanings in the Mengzi, and this usage prevails most when Dong Zhong-Shu's emphasis on sound glosses leads to the prosperity of New Texts studies and text divination. Then dictionaries such as the Explaining and Analyzing Characters and the Explaining Names use it to describe word origins instead. Under the influence of Zheng Xuan's annotations, zhi-yan is gradually used to explain word meanings, and this usage later becomes the mainstream of scholium studies.