ノーシーボalso: ノセボMeanings1nounnocebo; negative placebo responseMedical term for a harmful or unpleasant effect caused by a dummy treatment, opposite of プラセボ (placebo).Antonyms: プラセボノーシーボ効こう果かで、偽ぎ薬やくなのに副ふく作さ用ようが出でることがある。Due to the nocebo effect, side effects can occur even with a placebo.