Extreme or extremity — something that is very far from the average or moderate, or an action/opinion that goes to extremes.
彼の意見はいつも極端で、議論がまとまらない。
His opinions are always extreme, so discussions never reach agreement.
極端なダイエットは健康を害する可能性がある。
Extreme dieting can harm your health.
両極端ではなく、もっと中庸を心がけよう。
Rather than two extremes, let's aim for moderation.