動作主(どうさしゅ)performer of an action, agent, actor

動作主(どうさしゅ)は動作(どうさ)をしている人(ひと)のことです。

The performer of an action is the person who is carrying out the action.

「先生(せんせい)が挨拶(あいさつ)をした」の文(ぶん)の動作主(どうさしゅ)は先生(せんせい)である。

In the sentence "The teacher greeted," the performer of an action is the teacher.

古文(こぶん)では、動作主(どうさしゅ)や会話主(かいわぬし)が省略(しょうりゃく)される事(こと)が多(おお)いそうだ。

In classical Japanese, it seems that the performer of an action or the speaker in a conversation is often omitted.

文(ぶん)の構成(こうせい)の中(なか)で、その動詞(どうし)を直接的(ちょくせつてき)に担(にな)うものが動作主(どうさしゅ)なのだとか。

In the structure of a sentence, the one that directly carries out the verb is said to be the performer of an action.

読解力(どっかいりょく)が乏(とぼ)しいからか、文中(ぶんちゅう)の動作主(どうさしゅ)を見(み)つける事(こと)が難(むずか)しく感(かん)じます。

Perhaps due to my poor reading comprehension skills, I find it difficult to identify the performer of an action in the text.