He is considering taking an action against his neighbor for the fallen tree that damaged his property.

action 在这里指"法律诉讼"，源自法律术语"action at law"。这个词源于拉丁语"actio"，表示"行为、诉讼"。 在英语中，take an action against someone 是一个固定搭配，特指"对某人采取法律行动/提起诉讼"。