open

unfold, open

这两个动词均有“打开”之意。
unfold: 主要指把原来包好、卷好或叠好的东西再打开。
open: 普通用词，指把原来关起来或盖紧的东西打开。

名词 open:

1. a clear or unobstructed space or expanse of land or water
   同义词：clear
2. where the air is unconfined
   同义词：outdoors, out-of-doors, open air
3. a tournament in which both professionals and amateurs may play
4. information that has become public
   同义词：surface

动词 open:

1. cause to open or to become open
   同义词：open up
2. start to operate or function or cause to start operating or functioning
   同义词：open up
3. become open
   同义词：open up
4. begin or set in action, of meetings, speeches, recitals, etc.
5. spread out or open from a closed or folded state
   同义词：unfold, spread, spread out
6. make available
   同义词：open up
7. become available
   同义词：open up
8. have an opening or passage or outlet
9. make the opening move
10. afford access to
    同义词：afford, give
11. display the contents of a file or start an application as on a computer

形容词 open:

1. affording unobstructed entrance and exit; not shut or closed
   同义词：unfastened
2. affording free passage or access
3. with no protection or shield
   同义词：exposed
4. open to or in view of all
5. used of mouth or eyes
   同义词：opened
6. not having been filled
7. accessible to all
8. not defended or capable of being defended
   同义词：assailable, undefendable, undefended
9. (of textures) full of small openings or gaps
   同义词：loose
10. having no protecting cover or enclosure
11. (set theory) of an interval that contains neither of its endpoints
12. not brought to a conclusion; subject to further thought
    同义词：undecided, undetermined, unresolved
13. not sealed or having been unsealed
    同义词：opened
14. without undue constriction as from e.g. tenseness or inhibition
15. ready or willing to receive favorably
    同义词：receptive
16. open and observable; not secret or hidden
    同义词：overt
17. not requiring union membership
18. possibly accepting or permitting
    同义词：capable, subject
19. affording free passage or view
    同义词：clear
20. openly straightforward and direct without reserve or secretiveness
    同义词：candid, heart-to-heart
21. ready for business

1. Another supermarket opened last week.
   上星期又有一家超级市场开张了。
2. Don't lay yourself open to attack.
   不要让自己轻易受人攻击。
3. I'm not convinced your idea will work, but I'll keep an open mind for the moment.
   我还没想通是否你的意见可行，不过我先考虑一下。
4. The library is open from 9 to 6.
   那个图书馆从上午9点到下午6点开放。
5. He has an open mind in this matter.
   他在这个问题上虚怀若谷。
6. You may open a current account at a bank.
   你可以在银行开立一个活期帐户。

o.pen

adj.（形容词）

Affording unobstructed entrance and exit; not shut or closed.
开着的：没有障碍的进口和出口；没关的
Affording unobstructed passage or view:
通行无阻的：没有栅栏、界限或其它限制性边界的：
例句：
open waters; the open countryside.
开放的海域；开阔的村庄

Having no protecting or concealing cover:
没遮盖的：无保护的或无遮掩的：
例句：
an open wound; an open sports car.
没有包扎的伤口；敞篷跑车

Completely obvious; blatant:
显著的；露骨的：
例句：
open disregard of the law.
公然藐视法津

Carried on in full view:
公开的：
例句：
open warfare; open family strife.
公开的斗争；公开的家庭纠纷

Not sealed or tied:
未封上的：
例句：
an open package.
未封上的包裹

Spread out; unfolded:
打开的，未封住的：
例句：
an open book.
摊开的书

Having interspersed gaps, spaces, or intervals:
有空隙的；有间隔的：
例句：
open ranks; an open weave.
松散的队伍；织孔粗的编织

Accessible to all; unrestricted as to participants:
公开的，没有限制的：
例句：
an open competition.
公开赛

Free from limitations, boundaries, or restrictions:
不受限制的：
例句：
open registration.
自由登记

Enterable by registered voters regardless of political affiliation:
可自由参加的：不受政治因素干扰，通过民主投票产生的：
例句：
an open primary.
民主选举

Lacking effective regulation:
缺乏有影响力的管束的：
例句：
an open town in which gambling predominated.
准许赌赙的城市

Not legally repressed:
不受法律约束的：
例句：
open drug trafficking.
合法的毒品交易

Susceptible; vulnerable:
对…敏感的，易受攻击的：
例句：
open to interpretation; an issue that is open to question.
对翻译较敏感的；易引起争议的提议

Willing to consider or deal with:
待考虑或解决的：
例句：
open to suggestions.
广纳建议

Available; obtainable:
可利用的；可取得的：
例句：
The job is still open.
职位仍然空缺着

Available for use:
随时可用的：
例句：
an open account; the only course open to us.
活期的资金；我们唯一可用的途径

Ready to transact business:
营业中的：
例句：
The store is open.
这家商店正在营业

Not engaged or filled:
空闲的，未满的：
例句：
has an open hour for emergency cases.
有一个小时空闲处理紧急事件

Not yet decided; subject to further thought:
悬而未决的，仍需要考虑的：
例句：
an open question.
悬而未决的问题

Characterized by lack of pretense or reserve; candid:
毫无保留的，坦率的：
例句：
Please be open with me.See Synonyms at frank
请对我坦白参见 frank

Free of prejudice; receptive to new ideas and arguments:
没有偏见的：心平气和地对待新观点和争论的：
例句：
She listened to the proposal with an open mind.
她以无私的态度听取这项方案

Generous:
大方的，慷慨的：
例句：
He is very open with his time.
他非常乐意贡献自己的时间

Printing
【印刷术】
Widely spaced or leaded. Used of typeset or other printed matter.
有空格的，有间隔的：行距宽的，用于打字或打印
Having constituent elements separated by a space in writing or printing:
字间有空格的：在写作或打印中字间有空格的：
例句：
The wordsea gull is an open compound.
这个字海欧 是中间有空格的复合词

Music
【音乐】
Not stopped by a finger. Used of a string or hole of an instrument.
不用手指按压的：不用手指按住而通过弦或小孔结束的
Produced by an unstopped string or hole or without the use of slides, valves, or keys:
空弦所产生的：
例句：
an open note on a trumpet.
小喇叭的空音

Played without a mute:
不以弱音演奏的：
例句：
an open wind instrument.
不以弱音演奏的乐器

Articulated with the tongue in a low position, as the vowel infar.
以低音调发音的，象far 中的元音
Ending in a vowel or diphthong:
以元音或双元音结尾的：
例句：
an open syllable.
以元音结尾的音节

Designating a method of punctuation in which commas and other marks are used sparingly.
少用标点符号的：在不引起混淆的情况下可能时省略逗号和其他符号的
Being in operation; live:
运转中的，活生生的：
例句：
an open microphone.
正使用的麦克风

New England Clear. Used of weather.See Regional Note at fair
【新英格兰】 用于表示天气晴朗的参见 fair
Electricity Containing a gap across which electricity cannot pass.
【电学】 短路的
Mathematics
【数学】
Of or relating to an interval containing neither of its endpoints.
不包含前后两点的
Of, relating to, or being a set such that at least one neighborhood of every point in the set is within the set.
开集合的：指集合中的每一个点都有一个邻域，而且这些点全部在此集合中的
Of, relating to, or being a set that is the complement of a closed set.
余集合的
v.（动词）
o.pened,o.pen.ing,o.pens
v.tr.（及物动词）
To release from a closed or fastened position.
打开：从关闭的或固定的位置上移开
To remove obstructions from; clear.
除去，除掉，弄干净
To make or force an opening in:
切开，使畅通：
例句：
open an old wound.
切开旧伤口

To form spaces or gaps between:
区隔，间隔：
例句：
soldiers opening ranks.
士兵们错开队伍

To remove the cover, cork, or lid from.
从…上揭开盖子，瓶塞
To remove the wrapping from; undo.
打开…的包装；解开
To unfold so that the inner parts are displayed; spread out:
打开：打开使里面的内容表现出来；传播开来：
例句：
open a newspaper.
摊开或铺开一张报纸

To get (something) going; initiate:
举行，推动：
例句：
open a campaign.
举行一场运动

To commence the operation of:
开张，营业：
例句：
open a new business.
开始新的事业

Games To begin (the action in a game of cards) by making the first bid, placing the first bet, or playing the first lead.
【游戏】 叫牌，下财注，先出牌：在一种游戏的一圈或一盘的开始，叫牌，下财注，或先出牌
To make available for use:
开放：
例句：
opened the area to commercial development.
开放这个区域作为商业发展之用

To make more responsive or understanding.
使（心灵）更易接受…
To reveal the secrets of; bare.
泄密，表示心意
Law To recall (an order or a judgment) for a reexamination of its merits.
【法律】 撤消：（命令、审判）以便重新评估其是非曲折
v.intr.（不及物动词）
To become open:
使打开：
例句：
The door opened slowly.
这扇门慢慢地打开了

To draw apart; separate:
分开，分离：
例句：
The wound opened under pressure.
伤口因受力裂开了

To spread apart; unfold.
打开，散开
To come into view; become revealed:
展示，显现：
例句：
The plain opened before us.
一望无际的平原展现在我们面前

To become receptive or understanding.
（心灵）变得更容易接受…

To begin; commence:
开始，创始：
例句：
The meeting opened with a call to order.
这个会议是为了讨论社会治安而召开

To begin business or operation.
开始做生意或开始生产
To give the first public performance:
首次公开演出：
例句：
The play opens next week.
这出戏剧将于下星期公开演出

Games To make a bid, bet, or lead in starting a game of cards.
【游戏】 第一个叫牌，第一个下注，第一个打牌
To give access:
通往：
例句：
The room opens onto a terrace.
这个房间通往阳台

n.（名词）
An unobstructed area of land or water.
不设防的疆域或水域
The outdoors:
户外：
例句：
camping in the open.
露天宿营

An undisguised or unconcealed state:
坦然；公开：
例句：
brought the problem out into the open.
把这个问题拿出公开讨论

Sports Games A tournament or contest in which both professional and amateur players may participate.
【体育运动】 【游戏】 公开赛：专业和业余选手均可参加的比赛或锦标赛

<常用词组>open up
To spread out; unfold:
展开；摊开：
例句：
A green valley opened up before us.
青翠的山谷展现在我们眼前

To begin operation:
开始运作：
例句：
The new store opens up next month.
这家新商店将在下个月开张

To begin firing:
开战；开火：
例句：
The artillery opened up at dawn.
炮兵于拂晓时开口

Informal To speak freely and candidly:
【非正式用语】 直言不讳：
例句：
At last the frightened witness opened up and told the truth.
这名吓坏了的目击者终于直言不讳说出了事实

To make an opening in by cutting:
切开：
例句：
The surgeon opened up the patient`s chest.
这名外科医生切开了病人的胸部

To make available or accessible:
使可利用；使通往：
例句：
open up new markets.
打开了新的市场

Informal To accelerate. Used of a motor vehicle.
【非正式用语】 （用于汽车）加速
<习惯用语>open fire
To begin firing on.
开火
open (one`s) eyes
To become aware of the truth of a situation.
使看清事实真相
来源：
Middle English
中古英语
from Old English * see upo
源自 古英语 *参见 upo

【引伸】
o.penly
adv.（副词）
o.penness
n.（名词）