月亮渐盈， 直到正圆，然后消亏。

The moon waxes till it becomes full, and then wanes.

《新英汉大辞典》

我们现在知道地球不是正圆形的球体。

We now know the Earth is not a perfect sphere.

youdao

我们看到较圆的东西，我们会想到正圆。

We see something that's more or less round, and it reminds us of perfect circularity.

youdao

The number three is not a physical object, perfect roundness is not a physical object, perfect goodness is not a physical object.

数字三不是一个物理实体,正圆不是一个物理实体,真正的善良不是一个物理实体

耶鲁公开课 - 死亡课程节选

In fact, just because the world is round, you can already see if this is the Earth, to somebody that's the natural direction.

实际上,正由于地球是圆的,你们可以看到如果这是地球,对于某些人来说这才是惯常的方向

耶鲁公开课 - 基础物理课程节选

In order for a more or less round plate to remind me of roundness, Plato says, I have to have already met perfect roundness itself.

如果一个或多或少,有点圆的盘子能让我想到正圆,柏拉图认为,我必须已经见过完美的圆本身了

耶鲁公开课 - 死亡课程节选