against; contrary to; in contrast to
Expresses that something is contrary to expectations, rules, or a prediction.
This pattern is used when reality does not match what was expected, promised, or commanded. It often appears in news, essays, or formal speech, and it carries a sense of evaluation—the speaker is noting a contradiction with a stated standard or prediction. For example, if a product's sales were expected to be high but were low, you can say 予想に反して売り上げが低かった. It can also appear with words like 命令 (order), 期待 (expectation), 予想 (prediction), or 噂 (rumor).
To form it, simply place に反して after a noun. If you need to attach a verb, use the plain present form (dictionary form) followed by のに反して. This is not used with casual topics in daily conversation; it sounds slightly formal and literary, so it fits written reports, news, or speeches.