under² adv 1 under or below the surface of something 在下，在下面: He dived into the water and stayed under for over a minute. 他跳进水里，在水下停留了一分多钟。 2 less than the age, number, or amount that is mentioned 〔年龄、数字或数量〕小于; 少于; 低于: children aged nine and under 九岁及以下儿童