sterile: implies inability to reproduce or to bear fruit through or as if through an organic defect: a ~ imagination. （sterile主要有2个含义 1、贫瘠，不促进生长not able to support  growth，如sterile soil/fields贫瘠的土壤/田地  2、不育、无生育能力not able to produce children or young animals, etc，如sterile offspring不育子代，a sterile egg未受精卵，如sterile mind/imagination/debate/subject贫乏的思维/想象力/索然无味的辩论/主题，sterile needles无菌针头，表示clean and free of bacteria and germs清洁无细菌病菌；to sterilize绝育，如sterilize your cat/dog使你的狗/猫绝育）  sterile和fertile几乎完全对应，这段注释是从fertile拷贝改写的     organic defect生理缺陷器官缺陷


barren: basically applicable to a female or a marriage that does not produce offspring, may imply a lack of normal or expected return or profit: a ~ victory.     （barren有2个含义 1、贫瘠荒凉not good for plants to grow on it，如a barren desert/landscape不毛的沙漠/寸草不生的荒凉景色  2、女性不育，事业无收获not able to produce children or young animals，or to produce return or profit，如she is a barren woman她不能生育，如this is a barren argument/victory这是一场毫无收获的争论/胜利）


impotent: applies to the male and implies inability to copulate or reproduce: an operation that made him temporarily ~.    （如without the chairman's support, the committee is impotent没有主席的支持，委员会是无能为力的，如she blazed with impotent rage她发泄无能的怒火）


unfruitful: may replace barren in any of its applications with the emphasis on not bearing fruit: un ~ enterprise.   在词义上，fruitless比unfruitful更加强调毫无果实，因此也更失望


infertile: is often interchanged with sterile: an ~ egg; but it may imply deficiency rather than absence of fertility: an ~ strain of beef cattle.       an infertile couple/clinic/treatment一对不能生育的夫妇/不孕诊所/治疗


sterile不育: 指不能生育，或无助生长，或无创意，barren不育: 指女性不育，或指婚姻、事业等无收获，impotent不育: 指男性不育，或缺乏能力，unfruitful无果: 和barren可互换，更强调没有或缺乏成果，infertile低产贫瘠: 等于sterile，但可指低产而非不育


记忆方法: 1）首字母SBIUI想成USB II二代<==不育

              2）不育的意思是无生育能力mean lacking the power to produce offspring or bear fruit.