His criticism was directed at everybody who disagreed with him.

directed 是动词 direct 的过去分词形式，direct 的意思是"指向、对准"，这里表示"批评的矛头指向"。 at 是介词，在这里表示动作的目标或对象，指"针对、朝向"。 directed at 这个短语表示"针对...的、指向...的"，用来描述批评或指责的对象。