反义词是single，意思是单个，例如：
1、Many previously separate groups are now operating under the umbrella of a single authority.许多原本分散的团体现在正在单一的权威领导下运作。
2、Virtually all surface and near-surface terrestrial water occurs and moves as part of a single vast hydrologic system.实质上，所有地表水和接近地表的水是作为一个单一的大水文体系的一部分而存在和运动的。
3、Every single time he calls， I'm out.他每次打电话来我都不在家。