正反対(せいはんたい)

せいはんたい
noun
the exact opposite; diametrically opposed
1. the exact opposite; diametrically opposed
Completely and utterly opposite. Emphasizes that the contrast is total, not partial. Used for opinions, personalities, directions, and characteristics.
二人(ふたり)の性格(せいかく)は正反対(せいはんたい)だ。
Their personalities are the exact opposite.
あなたの意見(いけん)は私(わたし)と正反対(せいはんたい)ですね。
Your opinion is the complete opposite of mine.
駅(えき)から正反対(せいはんたい)の方向(ほうこう)に歩(ある)いてしまい、迷子(まいご)になった。
I walked in the exact opposite direction from the station and got lost.

Stronger than 反対(はんたい) alone. 正(せい) adds the sense of "exactly" or "precisely," making the opposition absolute.

Common patterns

Can function as a no-adjective: 正反対(せいはんたい)の意見(いけん) (the exact opposite opinion).