defense
词根词缀：
defend v. 保卫
de 加强 + fend 打击 → 保卫
defense n. 保卫
de 加强 + fens 打击 + e → 保卫
defenseless adj. 无防备的
defense 保卫 + less 无…的 → 无防备的
fend v. 抵挡，击退
offend v. 得罪
of〔= ob 加强〕+ fend 打击 → 一再打击〔别人〕→ 得罪
offender n. 罪犯；冒犯者
offend 得罪 + er 表名词 → 罪犯；冒犯者
offensive adj. 冒犯的
of 加强 + fens 打击 + ive …的 → 冒犯的
数据来源：新东方英语词汇速记大全
相关例句：
The boy could have felt sorry for himself and become depressed, or he could have adopted hardened cynicism as a defense.
这个男孩本有可能自怜自哀、抑郁消沉，也有可能采取冷酷的愤世嫉俗态度来保护自己。
It was first put to use in the Gulf War as a defense for Iraqi Scud missiles.
这个系统的首次应用是在海湾战争中，担任伊拉克飞毛腿导弹的防卫系统。
Twenty eight percent of the federal budget is spent on defense.
28%的联邦预算用于国防。
He sees the proposal as more of a diplomatic gambit than a serious defense proposal
在他看来，与其说这是一项精心筹划的国防动议，倒不如说是外交上的一着妙棋。
Defense experts say joint projects are increasingly squeezed by budget pressures.
国防专家说合作项目正迫于预算压力越来越受到压缩。
Our national defense capabilities and the army's defense and combat effectiveness have further improved.
国防实力和军队防卫作战能力进一步提高。