欠ける

欠ける

"To be lacking" or "to be chipped."

In this sentence, '欠ける' refers to a physical loss or waning, describing the moon losing its visible portion as it phases down from full moon.

月が欠け始めた。

The moon has started to wane.

Here, '欠ける' describes parts missing from a conceptual structure like a plan.

彼の計画にはいくつか欠けている部分がある。

There are some missing parts in his plan.

In this sentence, '欠ける' is used metaphorically to indicate the absence or deficiency of friendship in relationships.

友情が欠けると、人間関係が難しくなる。

When friendship is lacking, relationships become difficult.