却って【かえって】

却って says that something had the opposite effect to the one you expected: the medicine made you feel worse, the shortcut took longer. It is an adverb and goes in the second half of the sentence, just before the unexpected result. It is usually written in kana, かえって.

The first half sets up the expectation, often with きごう〜のに, きごう〜ようとしたら or きごう〜ために. Most of the time the result is worse than intended.

The reversal can also go the good way: something that looked like a setback turned out better.

却って or 逆に

ぎゃくに逆に ("conversely", "the other way round") can simply set two things side by side. 却って needs a cause that was expected to work one way and worked the other, so it cannot carry a plain comparison.

• × 兄は背が高いが、弟は却って低い → 兄は背が高いが、弟は逆に低い