formerly used as a treatment to reduce excess blood (one of the four humors of medieval medicine)
indiscriminate slaughter
同义词：bloodbath, bloodshed, battue
bloodletting详细解释
blood.let.ting n.（名词）Bloodshed.流血，杀戳The removal of blood, usually from a vein, as a therapeutic measure.放血：放血，静脉切开放血，作为测量治疗效果的一个方法The laying off of personnel or the elimination of resources.消耗：人员或资源的消耗 【引伸】 blood.let.ter n.（名词）
