An adverb meaning 'conversely' or 'on the contrary', indicating the opposite state or viewpoint; similar to 'rather' or 'instead'.
その説明は分かりにくかった。逆に混乱が増した。
That explanation was hard to understand. On the contrary, it increased confusion.
彼は運動が好きではない。逆に、家でゆっくりするのが好きだ。
He doesn't like exercise. Rather, he prefers to relax at home.
普通は上がると考えるが、この場合は逆に下がる可能性が高い。
Normally you'd expect it to rise, but in this case it's likely to fall instead.
逆に言えば、それが成功の条件だとも言える。
Conversely, you could say that that is a condition for success.