Every meaning of the common word “Qin (親)” in Chinese has been seen in ancient times. However, its meaning of “kiss” only appeared at the end of Ming Dynasty. Scholars generally believe that this meaning is derived from extended meaning, which is worth discussing. Before the Tang Dynasty, the meaning of “kiss” was only expressed by “Wu (嗚)” and its polyphonic form. “Xin (噷)” appeared in the Song Dynasty, “Qin (唚)” and “Qin (親)” appeared in the Ming Dynasty. “Qin (親)” and “Qin (唚)” are the phonetic loan character of “Xin (噷)”. As the tail vowel [-m] final vanishes and the confluence of sharp and rounded sounds, the three sounds tend to be the same, “Xin (噷)” is a rare word, the common writing “Qin (唚)” with the change of phonetic sign and homophone substitution word “Qin (親)” appeared in the folk. “Qin (親)” has the meaning of “contact”. It is easier to establish semantic association with the meaning of “kiss” and becomes the dominant word in the concept field of “kiss”. “Xin (噷)” and “Qin (唚)” exist only in spoken dialect. “Xin (噷)” is the subsequent character of “Xin (歆)”, the “kiss” meaning of “Xin (噷)” is an extension of the “smell” meaning of “Xin (歆)”. In order to find the source of words, we should use the method of finding words based on meaning and sound, combine with dialect materials, and link up the homophone and synonymy of variant words. Only by breaking through the restriction of glyphs, can we find out the writing form containing the etymological basis of many variant words.