“形聲” was originally called “象聲”. Later, Xu Shen changed the name of “four images” into “形聲” in ≪ShuowenJiezi·Xu≫. Apart from phonetic symbols, there are more important functions of sound symbols -- source indicating function. The function of indicating source, in short, that is, the function of phonetic symbols to show the phonetic and semantic relations of the words indicated by pictophonetic characters. There are four ways to infer the source of sound, symbol and meaning. The purpose of this paper is to deduce the etymological meaning of pictophonetic characters with “單” sound as the phonetic symbol.
There are five kinds of origin in the phonetic symbols of “單” sound, which are dynamic, be exhausted, fearful, comfortable and hard work. Among the origin of the pictophonetic characters with “單” sound, the pictophonetic characters with dynamic meanings are “戰, 彈, 僤”, the pictophonetic characters with be exhausted meaning are “鄲, 殫”, the ones with fear of righteousness are “戰, 憚, 譂, 嘽”, and the pictophonetic characters with comfortable meaning are “繟, 嘽, 闡”, the pictophonetic characters with hard work meaning are “憚, 癉”.