By A is meant B 是英语中一个惯用句型，通常用于给某事物下定义，其中A是被下定义部分（已知信息），B是下定义部分（新信息）。

By power is meant the rate of doing work. 功率是指做功的速率。

又如：

By acceleration is meant the rate of change of velocity with time. 加速度就是指速度对时间的变化率。

By automation is meant the technique of making a mechanical device or a process self-regulating and self-controlling. 自动化是指能使机械装置或操作过程进行自动调节和自动控制的技术。