柯林斯词典ppm 1. ABBREVIATION for parts per million 百萬分率[chem] 返回 ppm剑桥词典abbreviation for parts per million (= a unit for measuring the amount of a substance that is mixed with a liquid or another substance ) 百萬分之…(衡量物質與液躰或其他物質混郃時的度量單位，parts per million的縮寫） 返回 ppm