顧名思義，后置定語就是定語在所修飾詞的后面，短語、句子都可以作后置定語，甚至某些情況下，單詞也可以作后置定語。如：

There is something wrong with the machine.(單詞wrong作后置定語，修飾something)

The man standing under the tree is my brother.(短語作后置定語)

The man who is standing under the tree is my brother.(句子作后置定語，定語從句)。