Any of various systems of units for electricity and magnetism based on a system of equations in which the permeability of free space is taken as unity and by means of which the abampere is defined as the fundamental unit of current.电磁单位：建立在一系列反应或基础上的任何一个电磁单位制，自由空间的磁导率被当作单位，以此来定义安培为基本电流单位