The optimum or optimal level or state of something is the best level or state that it could achieve.
双语例句
例： Try to do some physical activity three times a week for optimum health.
试着每星期锻炼三次，以达到最佳的健康状态。
例： regions in which optimal conditions for farming can be created.
可为农耕创造最佳条件的地区。