above oneself

Acting with an undue opinion of one's own importance or abilities. / Acting without inhibition due to high spirits.

日本語の意味

自分の実際の能力や重要性を過大評価し、偉そうに振る舞う様子 / 高揚した状態で、普段の自分を超える大胆な振る舞いをする様子

After his first successful performance, he began to act above himself, ignoring the advice of his old mentors.

最初の大成功の後、彼は思い上がって昔の師匠たちの助言を無視するようになった。

意味（1）

Acting with an undue opinion of one's own importance or abilities.

意味（2）

Acting without inhibition due to high spirits.