It allows you to define the concept of a thermometer. You have three objects, one of them could be a thermometer.

从热的物体流向冷的物体,由此我们可以定义温度，我们还可以用它来定义温度计：

麻省理工公开课 - 热力学与动力学课程节选

So, zeroth law, then, allows you to define the concept of temperature and the measurement of temperature through a thermometer.

因此第零定律，使你可以定义温度的概念,以及通过温度计,测量温度的方法。

麻省理工公开课 - 热力学与动力学课程节选

But before you even do that, I want to define for you an important concept, which is the velocity at a given time, v .

但在这之前,我要给你们定义一个重要的概念,也就是给定时刻的瞬时速度v

耶鲁公开课 - 基础物理课程节选