1.arm用作动词的基本意思是“把…武装起来”,可以表示“提供”“配备”“支持”,也可以表示“以(武器)装备”。就目的而言可仅指为加强力量或安全做准备而提供,也可指为有效行为或作战而准备进攻或防御的装备。arm引申还可指精神上、道德上或身体上的准备。
2.arm可用作不及物动词,也可用作及物动词。用作及物动词时,以被武装的对象作宾语。

arm against(v.+prep.)
为对付…而武装起来; 对…加以防备 provide defence for oneself or sb with weapons, etc. against sth; guard against
〔说明〕 arm against不用于被动结构。
▲arm against sth
We bought the house to arm against big price rises.我们买了这处住宅,以防大涨价。
▲arm sb/oneself against sb/sth
We must arm the people against the lowering of our morals.我们必须武装人们的头脑,以防我们的道德标准降低。

arm for (v.+prep.)
武装…以备 supply sb with weapons for; prepare for
▲arm for sth
The soldiers armed for battle.士兵们拿起武器准备战斗。
▲arm sb/sth for sth
The nation must arm its soldiers for battle.国家必须为战士提供打仗武器。

arm with (v.+prep.)
用…武装; 向…提供 provide sb with weapons; provide with the means to gain sth
▲arm sb/oneself/sth with sth
They armed him with a rifle.他们发给他一支步枪。
John had armed himself with an excuse before he went to see the headmaster.约翰去见校长之前已经为自己准备好了一个借口。
◇ 用于be ～ed结构
The crowd were armed with broken bottles.那帮人手中备有碎酒瓶子。
The divers were armed with cameras and collecting gear.潜水员配备了照相机和收集用具。
A teacher should be armed with answers to questions that his pupils are likely to ask.一个教师应该准备好学生可能提出的问题答案。
The warship was armed with 16-inch guns.战舰配有16英寸口径大炮。

用作不及物动词
▲S+～(+A)
Their former enemy is arming again.他们从前的敌人正在重整军备。
War is certain, we should arm without delay.战争肯定要发生,我们必须立即武装起来。
用作及物动词
▲S+～+n./pron.
He said that both sides were arming themselves.他说双方都在武装着自己。
We must know how to arm ourselves.我们应该懂得怎样武装自己。
During World War II the United States armed many of its allies.第二次世界大战期间,美国为它的许多同盟国提供武器装备。
In colonial days the French armed the Indians to attack the British.在殖民地时期法国人武装印度人去抗击英国人。
◇ 用于be ～ed结构
The man was armed to the teeth.那人是全副武装。
其他
▲v-ing as Adverb.
Arming only with a short sword, he drove off five of his attackers.他只持一把短剑就赶跑了五名来犯者。
▲v-ed as Adverb.
Armed with such a precept, a number of doctors may slip into deceptive practices.有了这样一条指导原则,一些医生可能渐渐习惯于采取骗人的做法。

［派生词］ armed adj. 武装(到某种程度)的
［同义词］ n.  forearm v.  fit out, furnish, provide, supply
［词源］＜古英语earm＜拉丁语arma(臂)

1.arm用作名词的基本意思是“臂”,多指人的手臂、胳膊,也可指动物的前肢,亦喻指各种状似手臂的东西。
2.arm的复数形式arms,指“武器(尤指枪支)”。用于比喻时可指“权力”,也可指“兵种”,此时既不能带不定冠词,也不能为数词所修饰。用作定语时亦然。
3.arms可用在另一名词前作修饰语。
4.chance one's arm的意思是“冒险,做冒险的事”; give one's right arm的意思是“付出极大代价”。

arm in arm
挽臂,携手 with the arm of one person being passed through the bent arm of the other
The boys ran down the road arm in arm.孩子们手挽手沿着马路跑去。
The new couple walked arm in arm into the theatre.那对新婚夫妇手挽手的走进了剧院。

bear arms
从军,服兵役 join the army
In case of need, we must bear arms.在需要的时候,我们都必须从军。

go to arms
诉诸武力 settle the matter by the use of the army
Having failed to resolve their disputes at the conference table, the two countries went to arms.和平解决争端的努力失败以后,两国便诉诸武力。

make a long arm for
伸臂去拿某物 reach arms to catch sth
The monkey made a long arm for the peach.猴子伸臂去摘桃子。

twist arm
强迫 oblige sb to do sth
I've really had quite enough to eat, but perhaps if you twist my arm I could have just a little bit more.我真的吃得非常饱了,不过要是你硬要我再吃,也许我还可以吃一点。

He broke his arm in an accident.他在一次事故中折断了手臂。
They took me by the arm.他们抓住我的胳膊。
Every person has two arms, the right arm and the left arm.每个人都有两支手臂,左臂和右臂。
The right arm is usually stronger.右臂通常较强壮。
She put her arm around his neck and kissed him.她搂住他的脖子,吻了他。
Don't stay under the arm of a derrick!不要在起重机的吊臂下!
A hooligan put the arm on him last night when he was on his way home.昨晚在回家的路上,他遭到流氓的抢劫。
The policemen put the arm on the man until they could verify his story.警察把这个人扣留起来,等到核实了他没有问题以后才释放他。
They were not allowed to use arms.不许他们使用武器。
British policemen do not usually carry arms.英国警察通常不带武器。
People were up in arms against the invaders.人民拿起武器反抗侵略者。
There is no need to get up in arms about such trifles.为这样一些小事动火毫无必要。

arms, weapon
这两个词的共同意思是“武器”。其区别是：arms常用作复数形式,指专为战争而制造的兵器,如枪、炮,尤指士兵个人使用的具体的武器; weapon可用作单数形式或复数形式,指各种可用于进攻或防御的东西,如石块、木棍、枪炮、原子弹,也可用于借喻。例如：
The soldiers have enough arms.
士兵有足够的武器。
Guns and swords are weapons.
枪炮和刀剑都是武器。
He used the pen as his weapon.
他以笔作武器。

眼泪是女人的武器吗?
［误］ Are tears woman's arms?
［正］ Are tears woman's weapon?

with open arms, with open hands
参见open条。

1.抱着孩子的那个妇女是我的姨妈。
［误］  The woman who is carrying a child with her arms is my aunt.
［正］  The woman who is carrying a child in her arms is my aunt.
［析］  “抱着…”应说carry...in one's arms,其中介词不能用with,因为这里表示的是状态,而不是用某种工具。
2.有人给这些士兵提供美式武器。
［误］  These soldiers were provided with American arm.
［正］  These soldiers were provided with American arms.
［析］  arms作“武器”讲时,总是以复数形式出现,不能用作单数。
3.他抓住了我的胳膊。
［误］  He took me by my arm.
［正］  He took my arm.
［正］  He took me by the arm.
［析］  抓住某人身体的某部位用句型“take sb by the+n.(被抓的部位)”或“take sb's+n.”。

一般把arm(臂)和arms(武器)作为同形异义的词对待。