a quantity by which a given number (the multiplicand) is to be multiplied 乘数 ■(Economics)a factor by which an increment of income exceeds the resulting increment of saving or investment (经济)乘(或倍)数;收益增值率 ■a device for increasing by repetition the intensity of an electric current, force, etc. to a measurable level 倍增器,扩量(程)器 ■a type of fishing reel with a geared spool 齿轮轴钓鱼线