Abstract: There are now two nominations in current about Z=PV/RT, one is "压缩(性) 系数", the other is "压缩因数(子)".Calling Z "压缩(性) 系数" is very easy to make a confusion with compressibility C which is used to show the compressibiliy of some material. Such nominations may come from different Chinese translations of the term " Compressibility factor". It is concluded that "压缩因数" might be taken as a unified standard name for Z in order to facilitate academic exchange and prevent any confusion concept.