A case, occasion, or situation; a very commonly used noun to indicate circumstances (e.g., 'in the case of...').
雨の場合は試合を中止します。
The game will be cancelled in case of rain.
緊急の場合はこの番号に電話してください。
In an emergency, please call this number.
その場合、どう対処すればいいですか？
In that case, what should we do?