Unchallenged
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C1 adjective /ʌnˈtʃælɪndʒd/

Unchallenged

无可争议的; 被接受的没有反对; 没有对手
Meaning
not disputed or questioned; accepted without opposition; having no rival
Example
He remained the unchallenged champion for five years.
他五年保持不败的冠军。
A2 noun /ˈʌndərweər/

underwear

内衣
Meaning
Clothing worn beneath outer clothes, typically next to the skin.
Example
He bought new underwear for the trip.
他为旅行买了新的内衣。
C1 verb /ʌnˈɜːθ/

unearth

发掘
Meaning
To dig up from the ground or to discover something hidden.
Example
Archaeologists unearthed ancient artifacts at the site.
考古学家在遗址发掘了古代文物。
A2 adjective /ʌnˈhæp.i/

Unhappy

不快乐; 难过
Meaning
not happy; feeling sad or displeased; unfortunate or undesirable
Example
He was unhappy with the results of his exam.
他对考试结果感到不满。
C1 noun /ˈʌndərˌteɪkər/

undertaker

殡葬员
Meaning
A person whose job is to prepare the dead for burial and arrange funerals.
Example
The undertaker prepared the body for the funeral service.
殡葬员为葬礼服务准备了尸体。
B1 verb /juˈnaɪt/

unite

联合
Meaning
to join together or combine; to bring people or things together
Example
The crisis helped unite the community.
危机帮助团结了社区。
C1 noun /ˌʌnriˈælɪti/

unreality

非现实
Meaning
the state or quality of being unreal; lack of reality or truth
Example
The dreamlike setting gave the story a sense of unreality.
这种梦幻的场景让故事充满了非现实感。
B1 adjective /ʌnˈklɪər/

unclear

不清楚
Meaning
not easy to understand; vague or ambiguous
Example
The instructions were unclear, so I asked for clarification.
说明不清楚，所以我要求澄清。
B2 adjective /ʌnˈendɪŋ/

Unending

无尽的
Meaning
continuing forever; without end
Example
The unending rain made the day feel gloomy.
无尽的雨让这一天显得阴沉。
B2 adjective /ʌnˈwɪl.ɪŋ/

Unwilling

不愿意的; 不情愿的;
Meaning
not ready to do something; reluctant; not wanting to do
Example
He was unwilling to share his secret with anyone.
他不愿意与任何人分享他的秘密。
C1 adjective /ʌnˈkʌltʃəd/

Uncultured

不文明的; 无文化的
Meaning
lacking good manners, refinement, or education; uncivilized
Example
His uncultured behavior embarrassed everyone at the dinner party.
他在晚宴上的不文明行为让所有人感到尴尬。
B2 adverb /ʌnˈkaɪndli/

unkindly

残忍地
Meaning
in a cruel, harsh, or unsympathetic manner
Example
She spoke unkindly about her colleague during the meeting.
她在会议期间残忍地谈论了她的同事。
C1 verb /ˌʌndərˈlaɪ/

underlie

位于...之下
Meaning
to be the hidden cause or basis of something
Example
Strong cultural traditions underlie the community's practices.
强大的文化传统是社区实践的基础。
B2 adjective /ˌʌndɪˈstɜːrbd/

Undisturbed

未打扰
Meaning
not interrupted or interfered with; calm and peaceful
Example
She slept undisturbed for eight hours.
她睡了八个小时没有打扰。
A1 interjection /ʌ/

uh

呃
Meaning
a sound people make when they hesitate or are unsure what to say next.
Example
Uh, I’m not sure if that’s the right answer.
呃，我不确定这是不是正确的答案。
B2 adjective /ʌnˈriːzənəbəl/

unreasonable

不合理的
Meaning
not guided by reason or fairness; excessive or extreme beyond what is acceptable
Example
The manager made an unreasonable demand that no one could realistically meet.
经理提出了一个不合理的要求。
C1 verb /ʌnˈroʊl/

unroll

展开
Meaning
to open something that is rolled up; to spread out gradually
Example
She unrolled the map on the table to find the route.
她把地图在桌子上展开来寻找路线。
B2 adjective /ʌnˈtʃeɪndʒəbəl/

Unchangeable

不可改变的; 固定的;
Meaning
not able to be changed or altered; fixed and permanent
Example
The laws of physics are unchangeable principles that govern the universe.
物理法则是不变的原则，支配着宇宙。
A1 adjective /juːzd/

used

二手
Meaning
having already been used
Example
This is a used car.
这是一辆二手车。
C2 adjective /ʌnˈblʌʃɪŋ/

Unblushing

厚颜无耻的; 放肆的
Meaning
showing no shame or embarrassment; boldly shameless
Example
He told the unblushing lie without any hesitation.
他毫不犹豫地说了那个无耻的谎言。
B2 adjective /ʌnˈθɪŋkəbl/

Unthinkable

难以想象的
Meaning
impossible to conceive or imagine; beyond belief or consideration
Example
It was unthinkable that such a tragedy could happen in our peaceful town.
在我们和平的小镇上发生这样一场悲剧，简直是难以想象的。
B2 adjective /ʌnˈfeɪv(ə)rəbəl/

unfavorable

不利
Meaning
not beneficial or advantageous; showing disapproval or opposition
Example
The proposal received an unfavorable response from the committee.
提案收到了委员会的负面回应。
C1 verb /ʌnˈrævəl/

unravel

Meaning
To undo twisted or knitted threads; to solve or explain something complicated.
Example
The detective worked hard to unravel the mystery.
C2 verb /ˈʌndərˌraɪt/

underwrite

Meaning
To guarantee financial support, especially by agreeing to cover losses or risks; in insurance, to assess and accept risks.
Example
The bank agreed to underwrite the company's new bond issue.
C1 adjective ʌnˈskruːpjʊləs

unscrupulous

不道德的
Meaning
Having or showing no moral principles; not honest or fair.
Example
Unscrupulous peers can lead adolescents to delinquency.
不道德的同龄人可能会导致青少年犯罪。
C2 noun /ˈʌŋkʃən/

unction

涂抹
Meaning
The act of anointing as part of a religious or ceremonial ritual; excessive or insincere flattery.
Example
The priest performed the holy unction with solemnity.
牧师庄重地进行了神圣的涂抹仪式。
B1 adverb /ʌnˈjuːʒuəli/

unusually

异常地
Meaning
in a way that is not typical or expected; to an uncommon degree
Example
It was unusually cold for this time of year.
对一年中的这个时候来说，天气异常寒冷。
C1 noun /ʌnɪmˈpɔːrtəns/

unimportance

不重要
Meaning
the state or quality of being insignificant or not important
Example
He dismissed the issue with a sense of unimportance.
他以無關緊要的態度忽略了這個問題。
B2 adjective /ʌnˈwel.kəm/

Unwelcome

不受欢迎的; 不想要的; 不邀请的
Meaning
not wanted or accepted; not invited or pleasant
Example
The unwelcome news ruined their vacation plans.
不受欢迎的消息破坏了他们的度假计划。
B2 adverb /ʌnˈsɜːrtənli/

uncertainly

不确定地
Meaning
in a way that shows doubt or lack of certainty
Example
She glanced uncertainly at the complicated instructions.
她不确定地看着复杂的说明。
B1 adjective /ˈɜːrdʒənt/

Urgent

紧急
Meaning
requiring immediate action or attention; pressing
Example
The patient needs urgent medical attention.
病人需要紧急医疗照顾。
B2 adjective /ˈʌl.tɪ.mət/

Ultimate

最终的; 极致的; 终极的
Meaning
being the best or most extreme example of its kind; final; last
Example
This is the ultimate test of your skills.
这是你技能的终极考验。
C1 adjective /ˌʌnˈpɑr.də.nə.bəl/

Unpardonable

不可宽恕的
Meaning
too bad to be forgiven; inexcusable
Example
His betrayal of trust was an unpardonable offense.
他的背叛是不可原谅的罪行。
A2 noun /ˈʌndərwɛr/

Under wear

内衣
Meaning
clothing worn under other clothes, next to the skin
Example
She bought new underwear from the department store.
她在百货商店买了新的内衣。
C1 adjective /ʌnˈsaɪtli/

unsightly

难看
Meaning
Unpleasant to look at; ugly.
Example
The garbage pile created an unsightly view in the park.
垃圾堆在公园里创造了一个难看的景象。
B1 adjective /ˌʌnɪkˈspektɪd/

Unexpected

出乎意料的; 令人惊讶的
Meaning
not expected or anticipated; surprising
Example
The unexpected news left everyone speechless.
出乎意料的消息让所有人都哑口无言。
C1 adjective /ˌʌnfɔːrˈsiːn/

unforeseen

Meaning
Not anticipated or predicted; unexpected.
Example
The project faced unforeseen challenges that delayed its completion.
B2 adjective /ʌnˈprɒf.ɪ.tə.bl̩/

Unprofitable

无利可图
Meaning
not yielding profit or gain; not producing financial benefit
Example
The unprofitable business was forced to close down after three years.
这个无利可图的生意在三年后被迫关闭。
B2 adjective /ˈʌt.moʊst/

Utmost

最极; 极限
Meaning
greatest; most extreme; maximum possible
Example
She showed utmost care while handling the fragile items.
她在处理脆弱物品时表现出最大的关心。
B2 adverb /ʌnˈkɒnʃəsli/

unconsciously

无意识地
Meaning
without being aware of one's actions or surroundings
Example
She unconsciously tapped her foot to the rhythm of the music.
她无意识地跟着音乐的节奏轻轻跺脚。
C1 adjective /ʌnˈtɛnəbl/

untenable

无法维持
Meaning
not able to be maintained or defended against attack or objection
Example
The politician resigned when his position became untenable.
政治家在他的立场变得无法维持时辞职。
B1 adjective /ʌnˈnesəseri/

Unnecessary

不必要的；多余的
Meaning
not needed; not required; pointless
Example
The meeting was unnecessary since all decisions were already made.
会议是多余的，因为所有的决定已经做出。
B2 adjective /ʌnˈlɪmɪtɪd/

unlimited

无限
Meaning
without any limits or restrictions
Example
The internet plan offers unlimited data for the whole month.
该互联网计划提供整个一个月的无限数据。
C2 adjective /ˌʌnrɪˈmɪtɪŋ/

unremitting

不断的
Meaning
Never relaxing or stopping; persistent.
Example
Her unremitting efforts finally paid off.
她不懈的努力终于得到了回报。
C2 adjective /ˈʌndjʊləs/

undulous

波浪形的
Meaning
Having a wavy surface or form.
Example
The artist painted the undulous sea at sunset.
艺术家在日落时画了波浪形的海洋。
B2 verb /ˌʌndərˈɛstɪmeɪt/

underestimate

低估
Meaning
To judge something as less important or smaller than it really is.
Example
Never underestimate the power of teamwork.
永远不要低估团队合作的力量。
B2 verb /ʌnˈveɪl/

unveil

揭示
Meaning
to reveal or disclose something, especially in a formal manner
Example
The company will unveil a new product next week.
公司将在下周揭示一款新产品。
C2 noun /ˈjuːnɪvəˌlɛns/

univalence

单价性
Meaning
The state of having a single valence or combining power, especially in chemistry.
Example
Hydrogen is characterized by its univalence in chemical reactions.
氢气在化学反应中以其单价性为特点。
B1 adjective /ʌnˈwel/

Unwell

不舒服; 生病
Meaning
not in good health; feeling sick or ill
Example
She has been feeling unwell since yesterday.
她从昨天开始感到不舒服。
B1 adjective /ʌnˈnoʊn/

Unknown

未知
Meaning
not known or identified; unfamiliar
Example
The author of this letter remains unknown.
这封信的作者仍然未知。
C1 adjective /ʌnˈtaɪmli/

Untimely

不合时宜
Meaning
happening at an inappropriate or inconvenient time; premature
Example
His untimely death at the age of thirty shocked everyone.
他的过早死亡在30岁时震惊了所有人。
B1 adjective /ʌnˈmærid/

unmarried

未婚
Meaning
Not married; single.
Example
He is thirty-five and still unmarried.
他三十五岁，仍然未婚。
C2 adjective /ˌʌltrəˈmʌndeɪn/

ultramundane

超凡
Meaning
Relating to things beyond the physical world; supernatural or transcendental.
Example
Philosophers often discuss ultramundane realities beyond human perception.
哲学家们常常讨论超越人类感知的超凡现实。
A2 adjective /ˈʌɡ.li/

Ugly

丑陋的; 可憎的; 可怕的
Meaning
unpleasant or repulsive in appearance; morally reprehensible
Example
The old building looked ugly after years of neglect.
这座老建筑在多年疏忽之后看起来很丑。
C1 adjective /juːˈbɪkwɪtəs/

ubiquitous

无处不在
Meaning
Existing or being everywhere at the same time.
Example
Social media has become ubiquitous among young people.
社交媒体在年轻人中变得无处不在。
B1 verb /ʌnˈpæk/

unpack

拆开
Meaning
to remove items from a container; to explain or analyze something in detail
Example
After arriving home, she began to unpack her suitcase.
到家后，她开始拆开自己的行李箱。
C1 noun /ˌjuːnɪˈfɔːrməti/

Uniformity

一致性；统一性；相同状态
Meaning
the quality of being uniform; consistency or sameness
Example
The uniformity of the design created a pleasing visual effect.
设计的一致性创造了一个吸引人的视觉效果。
B2 adjective /ʌnˌkənˈfɜːmd/

Unconfirmed

未确认; 未验证;
Meaning
not confirmed as true or definite; not verified or substantiated
Example
The report remains unconfirmed until we receive official verification.
报告在我们收到官方验证之前保持未确认状态。
A1 verb /ˌʌndərˈstænd/

understand

理解
Meaning
to know the meaning of something; to comprehend
Example
Do you understand the instructions?
你理解这些指示吗?
B2 adjective /ˌʌnkənˈtroʊld/

uncontrolled

无法控制的
Meaning
not restrained or managed; lacking control
Example
The wildfire spread in an uncontrolled manner, causing widespread damage.
野火以无法控制的方式蔓延，造成广泛破坏。
B1 noun /ˈjuːs.fəl.nəs/

Usefulness

有用性
Meaning
the quality of being useful; practical value or helpfulness
Example
The usefulness of this tool became apparent during the project.
这个工具的有用性在项目过程中变得显而易见。
C1 adjective /ʌnˈkwaɪ.ət/

Unquiet

不安的; 焦虑的; 激动的
Meaning
restless; unable to remain still or quiet; anxious or troubled
Example
She spent an unquiet night worrying about the exam results.
她度过了一个不安的夜晚，担心考试结果。
C2 adjective /ʌnˈtɛmpərd/

untempered

失控的
Meaning
not moderated or softened; lacking proper balance or control
Example
The untempered anger of the crowd caused chaos.
人群的失控愤怒引发了混乱。
B2 adjective /ˌʌnəˈveɪləbəl/

unavailable

不可用
Meaning
Not able to be obtained, reached, or used; not present or accessible.
Example
The manager was unavailable to take calls during the meeting.
经理在会议期间不可用，无法接听电话。
C1 adjective /ˌʌndərˈhændɪd/

underhanded

阴险
Meaning
acting or done in a dishonest or secret way
Example
They exposed the company's underhanded dealings with its suppliers.
他们揭露了公司与供应商之间的隐秘交易。
C1 adjective /ʌnˈvɔɪst/

unvoiced

未表达
Meaning
not expressed in speech; in phonetics, a sound produced without vocal cord vibration
Example
The student kept her opinion unvoiced during the meeting.
学生在会议期间保持她的意见未表达。
B1 adjective /ʌnˈtru/

Untrue

错误的; 不正确的
Meaning
not true; false; incorrect
Example
His statement about the incident was completely untrue.
他关于事件的陈述完全是错误的。
C1 adjective /ʌnˈmaɪndfəl/

Unmindful

不留心的; 疏忽的;
Meaning
not paying attention; careless; heedless
Example
She was unmindful of the danger around her.
她没有注意到周围的危险。
A1 pronoun /ʌs/

us

我们
Meaning
used to refer to the speaker and one or more other people as the object of a verb or preposition
Example
She gave us a gift.
她给了我们一个礼物。
C1 noun /juːnəˈnɪməti/

Unanimity

一致性
Meaning
complete agreement among all members of a group
Example
The committee reached unanimity on the new policy.
委员会在新政策上达成了一致意见。
C2 verb /ˌʌndərˈɡɜːrd/

undergird

支持，强化
Meaning
to provide support or foundation for; to strengthen
Example
Strong values undergird a healthy society.
强大的价值观支撑着一个健康的社会。
B1 adjective /ʌnˈkaʊntəbəl/

Uncountable

无法计数的; 无穷的
Meaning
too many to be counted; innumerable; infinite in quantity
Example
There are uncountable stars in the night sky.
夜空中有无数的星星。
B2 verb /ʌnˈfəʊld/

unfold

展开或打开
Meaning
to open or spread out something that was folded; to gradually reveal or develop
Example
She unfolded the letter carefully.
她小心地展开了信件。
C2 adjective /ˈʌndjʊleɪtɪŋ/

undulating

波动的
Meaning
Having a smoothly rising and falling form or motion like waves.
Example
We drove through undulating hills.
我们驱车穿过起伏的山丘。
C1 verb /ʌnˈnɜːrv/

unnerve

失去信心
Meaning
to make someone lose confidence, courage, or composure
Example
The hostile questions began to unnerve the witness.
敌对问题开始让证人感到不安。
C1 adjective /ˌʌnrɪˈfaɪnd/

unrefined

未精炼的
Meaning
not processed or purified; lacking polish or sophistication
Example
The unrefined oil must be processed before it can be used as fuel.
未精炼的石油在用作燃料之前必须进行加工。
C1 noun /ˈʌp.ʃɒt/

Upshot

结果; 结论
Meaning
the final result or outcome of a series of events; conclusion
Example
The upshot of the meeting was a decision to postpone the project.
会议的结果是决定推迟项目。
C1 noun ˌʌndərˈprɪvəlɪdʒd ɡruːps

underprivileged groups

贫困群体
Meaning
Groups of people who lack basic necessities or advantages that are available to other members of society.
Example
Underprivileged groups benefit from social initiatives.
贫困群体从社会倡议中受益。
B2 verb /ˌʌndərˈmaɪn/

undermine

削弱
Meaning
to gradually weaken or damage something or someone
Example
Constant criticism can undermine a child's confidence.
持续的批评可能会削弱孩子的自信心。
B2 verb /ʌnˈtaɪ/

untie

解开
Meaning
to loosen or remove a knot or binding; to release something that is tied
Example
She untied the rope to free the boat.
她解开绳子来释放船只。
C1 noun /ˈʌp.raɪt.nəs/

Uprightness

正直; 正义
Meaning
the quality of being honest and morally correct; integrity
Example
His uprightness in business dealings earned him great respect.
他在商业中的正直赢得了很大的尊重。
C2 adjective /ʌnˈtiːtʃəbəl/

unteachable

不可教的
Meaning
not able or willing to learn; resistant to instruction or guidance
Example
He was so stubborn that he became almost unteachable.
他非常固执，几乎变得不可教。
B2 verb /ˌʌndərˈteɪk/

undertake

承担
Meaning
to commit to and begin a task or project; to take on responsibility
Example
She decided to undertake a challenging project.
她决定承担一个具有挑战性的项目。
B2 adjective /ˌʌnəˈfɪʃ.əl/

Unofficial

非官方的
Meaning
not officially authorized or confirmed; informal
Example
The unofficial results showed a close race.
非官方的结果显示出一场激烈的比赛。
A2 preposition /əˈpɒn/

upon

之后
Meaning
on or immediately after
Example
Upon hearing the news, he rushed to the hospital.
听到消息后，他赶到医院。
C1 adjective /ʌnˈkwes.tʃən.ə.bl̩/

Unquestionable

无可争议的; 确定的
Meaning
not able to be disputed or doubted; certain and beyond doubt
Example
Her honesty and integrity are unquestionable qualities.
她的诚实和正直是无可争议的品质。
C2 noun /ˈʌn.dɚˌstɔː.ri/

understory

下层植被
Meaning
The layer of vegetation beneath the main canopy of a forest.
Example
The understory of a rainforest is home to small mammals and insects.
雨林的下层植被是小型哺乳动物和昆虫的家园。
C1 noun /ʌpˈhiːvəl/

upheaval

动荡
Meaning
a violent or sudden change or disruption to something
Example
The company faced a major upheaval after the sudden resignation of its CEO.
公司在其CEO突然辞职后经历了巨大的动荡。
C2 adjective /ʌnˈwəʊntɪd/

unwonted

不寻常
Meaning
Unusual, uncommon, or out of the ordinary.
Example
She spoke with an unwonted gentleness that surprised everyone.
她以一种不寻常的温柔说话，令所有人都感到惊讶。
C2 adjective /ʌnˈflæpəbəl/

unflappable

冷静沉着
Meaning
calm and composed, especially in difficult situations
Example
Despite the crisis, he remained unflappable and confident.
尽管面临危机，他依然保持冷静沉着，充满自信。
C2 verb /ʌpˈhiːv/

upheave

抬起
Meaning
to lift or raise something forcefully; to cause to rise suddenly
Example
The workers had to upheave the heavy stone to clear the path.
工人们不得不抬起重石来清理道路。
C1 adjective /ˌʌnrɪˈkwaɪtɪd/

unrequited

Meaning
Not returned or reciprocated, especially in the context of love or affection.
Example
He suffered from unrequited love for years.
B2 adverb /ˈʌt.ə.li/

Utterly

完全地; 绝对地; 完整地
Meaning
completely; absolutely; totally
Example
The movie was utterly boring and I fell asleep.
电影完全无聊，我睡着了。
C1 adjective /ˌʌnəˈsjuːmɪŋ/

unassuming

谦虚
Meaning
Not pretentious or arrogant; modest.
Example
Despite his success, he remained unassuming and humble.
尽管他取得了成功，他仍然谦虚和谦逊。
B2 verb /ʌnˈkʌvə(r)/

uncover

揭示
Meaning
to reveal something that was hidden or secret
Example
The investigation uncovered new evidence.
调查揭示了新的证据。
C1 adjective ʌnˈtʃɑːtɪd

uncharted

未标记
Meaning
Not mapped or surveyed; unknown or unexplored.
Example
The mission aimed to explore uncharted areas of the planet.
该任务旨在探索星球上未标记的区域。
B2 adjective /ʌnˈfeɪ.vər.ə.bəl/

Unfavourable

不利的; 逆境的
Meaning
not helpful or advantageous; adverse
Example
The weather conditions were unfavourable for our outdoor event.
恶劣的天气条件不利于我们的户外活动。
C1 adjective /ʌnˈdɔːntɪd/

Undaunted

无畏的; 勇敢的; 不屈的;
Meaning
not intimidated or discouraged by difficulty, danger, or disappointment
Example
Despite the setbacks, she remained undaunted in pursuing her goals.
尽管遇到挫折，她在追求目标时依然无畏。
C2 verb /ʌnˈfrɒk/

unfrock

剥夺神职
Meaning
To remove a priest from his position or deprive someone of a rank.
Example
The corrupt priest was unfrocked after the investigation.
腐败的牧师在调查后被解除职务。
B2 adjective /ʌnˈwɜːrði/

Unworthy

不配; 没有价值
Meaning
not deserving respect or attention; lacking worth or merit
Example
He felt unworthy of such praise and recognition.
他觉得自己不配得到这样的赞扬和认可。
B1 adjective /ʌnˈsɜːrtən/

Uncertain

不确定
Meaning
not able to be relied on; not known or definite; not having reliable knowledge
Example
I am uncertain about my future career plans.
我对未来的职业规划感到不确定。
A2 verb /ʌpˈdeɪt/

update

更新
Meaning
to make something more modern or current; to provide new information
Example
Please update your software regularly.
请定期更新您的软件。
B2 adjective /ʌnˈsiːn/

Unseen

看不见的；未曾看到或注意到的
Meaning
not previously seen or noticed; invisible; hidden
Example
The unseen forces of nature can be very powerful.
自然界的看不见的力量可能非常强大。
C1 adjective /ˌʌnˈɪntɪmeɪtɪŋ/

unintimating

没有暗示
Meaning
Not giving a hint or suggestion; not indicating.
Example
His unintimating tone gave no clue of his true feelings.
他的没有暗示的语气没有透露他真正的感受。
C1 adjective /ʌnˈtoʊld/

Untold

不可计数的; 无尽的
Meaning
very great in amount or degree; countless; immeasurable
Example
The earthquake caused untold damage to the city.
地震对城市造成了无法计数的损害。
C1 verb /ʌpˈruːt/

uproot

拔除
Meaning
To pull something out of the ground; to remove or displace completely.
Example
They uprooted the old tree from the garden.
他们从花园里把老树拔了出来。
B1 adjective /ʌnˈeɪ.bəl/

Unable

无法
Meaning
lacking the power, skill, or means to do something
Example
He was unable to attend the meeting.
他无法参加会议。
C1 adjective /ˌʌn.əˈdʌl.tə.reɪ.tɪd/

Unadulterated

纯净的
Meaning
not mixed or diluted with any different or extra elements; pure
Example
She felt unadulterated joy when she heard the news.
当她听到这个消息时，她感到纯净的快乐。
C1 adjective /ʌnˈwɪtɪŋ/

unwitting

无意的
Meaning
Not aware of what is happening; done without realizing.
Example
She became an unwitting participant in the scam.
她成了这场骗局中的一个无意的参与者。
C2 adjective /ʌnˈtʃeɪst/

Unchaste

不道德的; 不纯洁的;
Meaning
not celibate; having engaged in sexual relations; lacking moral purity
Example
The conservative society considered her behavior unchaste and improper.
保守的社会认为她的行为不道德和不合适。
B2 noun /ʌnˈkaɪndnəs/

unkindness

不友善
Meaning
lack of kindness; cruel or inconsiderate behavior
Example
His unkindness hurt her feelings deeply.
他的不友善深深伤害了她的感情。
B2 adjective /ʌnˈsteɪbəl/

Unstable

不稳定
Meaning
likely to change; not steady or secure; unsteady
Example
The unstable economy made people worried about their jobs.
不稳定的经济让人们担心他们的工作。
B2 adjective /ʌnˈnætʃərəl/

Unnatural

不自然的
Meaning
not existing in nature; artificial; forced
Example
The actor's smile looked unnatural and forced.
演员的笑容看起来很不自然，很勉强。
C2 adjective /ɜːrˈbeɪn/

urbane

都市的
Meaning
showing polished manners, refinement, and sophistication
Example
He was an urbane gentleman who charmed everyone at the party.
他是一个都市绅士，在派对上迷住了所有人。
C1 verb /ˌʌndərˈsteɪt/

understate

低估
Meaning
To describe something as being less important or serious than it really is.
Example
He tends to understate his achievements.
他倾向于低估自己的成就。
B2 noun /ʌnˈkɒnʃəsnəs/

unconsciousness

无意识
Meaning
the state of being unaware of and unable to respond to one's surroundings
Example
After the accident, he was in a state of unconsciousness for several hours.
事故后，他昏迷了几个小时。
C1 adjective /ʌlˈtɪəriər/

ulterior

隐藏的动机
Meaning
hidden or secret, often with a selfish motive
Example
He invited her with an ulterior motive.
他带着隐藏的动机邀请了她。
B1 noun /ˌʌnɪmˈplɔɪmənt/

Unemployment

失业
Meaning
the state of being unemployed; lack of paid work
Example
The unemployment rate has increased significantly this year.
今年失业率显著上升。
A1 adjective /ˈjuːs.fəl/

Useful

有用的; 实用的
Meaning
having a beneficial purpose; practical
Example
This tool is very useful for fixing problems.
这个工具对解决问题非常有用。
B2 adjective /ʌnˈkwɒl.ɪ.faɪd/

Unqualified

不合格的; 无资格的;
Meaning
not having the necessary skills or qualifications; complete or absolute
Example
He was unqualified for the engineering position due to lack of experience.
他因缺乏经验而不适合这个工程职位。
A2 noun /ˈjuːnɪt/

unit

单元
Meaning
an individual thing or person regarded as a single and complete entity
Example
Each unit in the production line is carefully tested.
生产线上的每个单元都经过仔细测试。