radioactivity
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B2 noun ˌreɪ.di.oʊ.ækˈtɪv.ə.ti

radioactivity

Meaning
The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
Example
Radioactivity is used in medical treatments like cancer therapy.
B2 verb /ˈræl.i/

rally

Meaning
to come together for a common purpose or to recover strength or spirit
Example
The team rallied after halftime and won the match.
C1 verb /rænt/

rant

Meaning
to speak or shout in an angry, uncontrolled way
Example
He ranted about the unfair treatment at work.
C2 adjective /rɪˈfjuː.tə.bəl/

Refutable

Meaning
capable of being proven wrong or false; able to be disproved
Example
His theory was refutable because it could be tested experimentally.
B2 adjective /ˌrez.ɪˈden.ʃəl/

residential

Meaning
Designed for people to live in.
Example
The institution was fully residential.
B2 verb /ˌriːprəˈdjuːs/

reproduce

Meaning
To make a copy of something; to generate offspring.
Example
Many animals reproduce rapidly in favorable conditions.
B2 noun ˈruθləs ˌkɑmpəˈtɪʃən

ruthless competition

Meaning
Fierce and merciless rivalry or contest, without pity or compassion.
Example
Ruthless competition for power leads to societal issues.
B2 noun /ˈraɪvəlri/

Rivalry

Meaning
competition for the same objective or for superiority in the same field; the state of being rivals
Example
The rivalry between the two teams made the match exciting.
C1 adjective /rɪˈvenʒ.fəl/

Revengeful

Meaning
seeking or desiring revenge; vindictive
Example
He became revengeful after being betrayed by his friend.
B2 noun rɪˈzɪl.i.əns

resilience

Meaning
The ability to recover quickly from difficulties; toughness.
Example
Testing the resilience of wood is crucial.
C1 adjective /rɪˈper.ə.bəl/

Repairable

Meaning
able to be fixed or mended; capable of being repaired
Example
The broken phone is repairable with the right parts.
C1 noun /rɪˈkɒnɪsəns/

reconnaissance

Meaning
A survey or exploration, especially for military or strategic purposes.
Example
The soldiers conducted a reconnaissance of the enemy camp.
B1 noun /ruːt/

Root

Meaning
the part of a plant that grows underground; the basic cause, source, or origin of something
Example
We need to find the root of this problem to solve it permanently.
C1 verb /rɪˈtrækt/

retract

Meaning
to withdraw a statement, promise, or part of the body; to pull back
Example
The company retracted its earlier statement after realizing the error.
B1 noun ˌrekəɡˈnɪʃn

recognition

Meaning
Acknowledgment of the existence, validity, or legality of something; appreciation or acclaim for an achievement, service, or ability.
Example
He earned recognition after years of struggle.
C2 noun /ˌrɛtroʊˈɡrɛʃən/

retrogression

Meaning
a return to a worse or less developed state
Example
The country experienced economic retrogression after the crisis.
B2 noun, verb /rɪər/

rear

Meaning
the back part of something; to bring up or raise children or animals
Example
The mother cat reared her kittens in a quiet corner.
B1 verb /ˈrɛdʒɪstər/

register

Meaning
To enter or record officially on a list or in a book.
Example
You must register for the conference before the deadline.
B2 adjective /ˈreɪʃəl/

racial

Meaning
relating to a race of people
Example
Racial equality is an important issue in many societies.
C1 noun /rɪˈsaɪtl/

recital

Meaning
A performance of music, dance, or poetry, usually by a soloist.
Example
She gave a piano recital at the concert hall.
B2 noun rɪˈpʌb.lɪk

republic

Meaning
A state in which supreme power is held by the people and their elected representatives, with an elected or nominated president rather than a monarch.
Example
A republic is governed by representatives of the people.
C1 noun /ˌrɛfəˈrɛndəm/

referendum

Meaning
a general vote by the population on a single political issue
Example
The government held a referendum on the new constitution.
C2 noun /ˈreɪləri/

raillery

Meaning
good-humored teasing or joking
Example
Their friendship was full of light-hearted raillery.
B1 noun /rɪˈsɜːtʃə(r)/

researcher

Meaning
a person who conducts research
Example
The researcher published her findings in a scientific journal.
B2 noun, verb /ˈriːteɪl/

retail

Meaning
the sale of goods to the public in small quantities for use or consumption rather than for resale
Example
The company specializes in the retail of clothing and accessories.
B2 adjective /rɪˈfaɪnd/

Refined

Meaning
elegant and cultured in appearance, manner, or taste; purified
Example
She has very refined taste in art and music.
B2 noun /rɪˌlaɪəˈbɪləti/

reliability

Meaning
the quality of being trustworthy or performing consistently well
Example
Customers value the reliability of our service.
B1 verb /rɪˈfɜː/

refer

Meaning
to mention or allude to something; to direct someone to a source of information
Example
Please refer to page 45 for more details.
B2 noun/adjective /rɪˈpʌblɪkən/

republican

Meaning
a member or supporter of a republican political party or system
Example
The republican candidate won the election.
B2 noun /rɪˈsiː.vər/

Receiver

Meaning
a person or thing that receives something; the part of a telephone containing the earpiece and mouthpiece
Example
She picked up the receiver to answer the phone call.
A2 verb /ˈriːəlaɪz/

realize

Meaning
to become aware of; to understand clearly; to achieve or make real
Example
I didn't realize how late it was until I checked the clock.
B2 noun /ˈrækɪt/

racket

Meaning
A piece of equipment used to hit the ball in sports like tennis or badminton; also a loud noise or an illegal scheme.
Example
He bought a new tennis racket for the match.
C2 adjective /rɪˈfræktəri/

refractory

Meaning
Stubborn or resistant to control, authority, or treatment.
Example
The refractory child refused to follow the teacher's instructions.
B2 noun /roʊˈteɪʃən/

Rotation

Meaning
the action of rotating around an axis or center; a single turn
Example
The Earth's rotation takes 24 hours to complete.
C1 adjective /ˈrɛtroʊˌɡreɪd/

retrograde

Meaning
moving backward or returning to a worse condition
Example
The policy was seen as a retrograde step for human rights.
C1 adjective /ˈrek.wɪ.zɪt/

Requisite

Meaning
made necessary by particular circumstances; required
Example
Good communication skills are requisite for this job.
C1 verb /ˌriː.kənˈviːn/

reconvene

Meaning
to gather or assemble again, especially for a meeting
Example
The committee will reconvene after lunch.
C1 noun /ˈrɛvərəns/

reverence

Meaning
deep respect for someone or something
Example
The students showed reverence to their teacher.
C2 verb /rɪˈɡeɪl/

regale

Meaning
To entertain or amuse someone with stories, food, or drink.
Example
He regaled us with stories of his travels around the world.
B2 noun, verb /ræŋks/

ranks

Meaning
Positions within a group, especially in a hierarchy or organization.
Example
He quickly moved up the ranks of the army.
B1 verb /ˈreskjuː/

rescue

Meaning
to save someone or something from danger or harm
Example
The firefighters rescued the cat from the tree.
C2 adjective /rɪˈfrɪndʒənt/

refringent

Meaning
Capable of refracting light or other waves.
Example
The refringent properties of the crystal bent the light into a spectrum.
C2 verb /rɪˈtrɛntʃ/

retrench

Meaning
to reduce costs, spending, or staff to save resources
Example
The company had to retrench employees due to financial difficulties.
C1 noun ˈrɔɪəl ˈbɛŋɡəl ˈtaɪɡər

Royal Bengal Tiger

Meaning
A subspecies of tiger found primarily in India and Bangladesh, known for its distinctive orange coat with black stripes.
Example
The Royal Bengal Tiger is an iconic species of the Sundarbans.
C2 verb /rɪˈfrækt/

refract

Meaning
To bend light, sound, or heat as it passes through a medium.
Example
The water refracts light, making the straw look bent.
C1 verb /ˈrævɪdʒ/

ravage

Meaning
to cause severe and extensive damage or destruction
Example
The hurricane ravaged the coastal villages.
B1 verb /rɪd/

rid

Meaning
to remove or get rid of something
Example
I need to rid the house of all the clutter.
B2 verb /rɪˈkɔːl/

recall

Meaning
to bring (a memory, fact, or situation) back into one's mind
Example
I can't recall the last time we met.
C1 adjective /raɪf/

rife

Meaning
widespread or common, often in a negative sense
Example
Corruption was rife in the old government system.
C2 adjective /rɪˈprɛsəbl̩/

repressible

Meaning
Capable of being restrained or suppressed.
Example
The movement proved to be hardly repressible.
C2 verb /ˈrʌstɪkeɪt/

rusticate

Meaning
To go to the countryside or to suspend someone from university.
Example
He decided to rusticate in the village to escape the busy city life.
C1 verb /rɪˈvɪər/

revere

Meaning
To deeply respect or admire someone or something.
Example
The students revered their teacher for his wisdom.
B2 noun /rɪˈmeɪnz/

remains

Meaning
the parts, pieces, or substances that are left after the rest has been used or removed
Example
The remains of the meal were left on the table.
C1 noun /ˌrɛpəˈreɪʃən/

reparation

Meaning
the making of amends for a wrong done by paying money or helping those who were wronged
Example
The government offered reparations to the victims of the conflict.
A2 noun rɪˈspɛkt

respect

Meaning
A feeling of deep admiration for someone or something.
Example
We should show respect to the freedom fighters.
C1 noun, adjective /ˈrɛvərənd/

reverend

Meaning
A title of respect used for members of the clergy; deserving deep respect.
Example
The Reverend gave an inspiring sermon at the church.
B2 verb /ˈræm.bəl/

ramble

Meaning
to talk or write at length in a confused or inconsequential way; to walk for pleasure without a fixed route.
Example
He rambled on about his childhood for hours.
B2 noun /ˈriːteɪlər/

retailer

Meaning
a person or business that sells goods to consumers rather than to other businesses
Example
The retailer offers discounts on electronic products.
C1 verb /ˌriːˈsiːt/

reseat

Meaning
to seat someone again or to fit something back into its place
Example
The usher had to reseat the guests after the interruption.
C1 adjective /rɪˈpʌl.sɪv/

Repulsive

Meaning
extremely unpleasant; causing strong dislike or disgust
Example
The smell of rotten eggs was absolutely repulsive.
C1 verb /ˌriːɪmˈbɜːrs/

reimburse

Meaning
to pay back money to someone who has spent it or lost it
Example
The company reimbursed him for travel expenses.
C2 noun /ˈrɛd.ə.ləns/

redolence

Meaning
a pleasant smell or the quality of suggesting something strongly
Example
The redolence of jasmine filled the evening air.
A2 adverb /ˈrɛə(r)li/

rarely

Meaning
not often, infrequently
Example
She rarely eats sweets because of her diet.
A1 noun ˈræbɪt

rabbit

Meaning
A small mammal with long ears, long hind legs, and a short tail
Example
The rabbit ran quickly into the forest.
C1 noun /ˈrɛɡjəleɪtər/

regulator

Meaning
a person or device that controls or maintains the operation of a system
Example
The government appointed a new regulator for the financial sector.
A2 verb /rɪˈmeɪn/

remain

Meaning
to stay in the same place; to continue to exist
Example
Only a few guests remain at the party.
B2 noun ˌrɛvəˈluːʃən

revolution

Meaning
A forcible overthrow of a government or social order, in favor of a new system.
Example
The story is set during the French Revolution.
B1 adjective /ˈrel.ə.vənt/

Relevant

Meaning
closely connected or appropriate to what is being discussed; pertinent
Example
Please provide only relevant information for this discussion.
C1 noun rɪˈdʌndənsi

redundancy

Meaning
The state of being not or no longer needed or useful; superfluousness.
Example
The redundancy in the company's workforce led to many layoffs.
C1 adjective /ˈrɪvɪtɪŋ/

riveting

Meaning
extremely interesting; holding the complete attention
Example
The movie was so riveting that nobody looked away.
C1 verb rɪˈpel

repel

Meaning
To push away or force apart due to similar charges or properties.
Example
Protons repel each other.
C2 noun /ˈrʊkəri/

rookery

Meaning
a place where rooks or other birds breed and nest in colonies
Example
We saw a rookery full of noisy birds near the forest.
B1 noun rəʊlz

Roles

Meaning
A person's or thing's function in a particular situation.
Example
Defined roles improve team performance.
B2 adjective /rɪˈɡret.ə.bəl/

Regrettable

Meaning
causing or deserving regret; unfortunate; deplorable
Example
It is regrettable that so many talented people left the company.
B2 verb /ˌriːəˈreɪndʒ/

rearrange

Meaning
to change the order or position of something
Example
She decided to rearrange the furniture in her living room.
C1 verb /rɪˈmjuːnəreɪt/

remunerate

Meaning
To pay someone for services or work done.
Example
The company will remunerate employees fairly for their overtime.
B1 adjective /rɔː/

Raw

Meaning
uncooked; not processed; in natural state; inexperienced
Example
The chef prefers to use raw vegetables in his salads.
C2 noun /ˈrɛkwiəm/

requiem

Meaning
A mass, music, or ceremony for the repose of the souls of the dead.
Example
The choir performed a requiem in memory of the late leader.
B2 verb /rɪˈdʒɔɪs/

rejoice

Meaning
to feel or show great joy; to celebrate
Example
The family rejoices at the good news.
C1 noun /ˌræʃəˈnæl/

rationale

Meaning
the underlying reason or explanation for something
Example
The rationale behind his decision was clearly explained.
A2 noun ˈrɛlətɪvz

Relatives

Meaning
A person connected by blood or marriage; a kinsman or kinswoman.
Example
Relatives can help you build a complete family tree.
C2 adjective /ˌriːkruːˈdɛsənt/

recrudescent

Meaning
reviving or breaking out again after a period of abatement
Example
Recrudescent tensions threatened the fragile ceasefire.
C1 verb /ˌrevəˈluːʃənaɪz/

revolutionize

Meaning
Change (something) radically or fundamentally.
Example
Artificial intelligence is set to revolutionize the healthcare sector.
C1 noun /ˈroʊ.lɪŋ bɔːrd/

Rolling board

Meaning
a flat wooden or marble surface used for rolling out dough
Example
She placed the dough on the rolling board.
C1 noun /ˈrɛspɪt/

respite

Meaning
A short period of rest or relief from something difficult or unpleasant.
Example
The weekend provided a welcome respite from work.
B2 noun /ˈrʊki/

rookie

Meaning
a person who is new to an activity or organization; a beginner
Example
The rookie policeman made a few mistakes on his first day.
C2 noun /rɪˌkrɪmɪˈneɪʃən/

recrimination

Meaning
an accusation made in response to an accusation; mutual blaming
Example
The debate quickly descended into mutual recriminations.
C1 noun /roʊt/

rote

Meaning
mechanical or habitual repetition, often without understanding
Example
He learned the poem by rote without understanding its meaning.
C1 adjective rɪsk-ədˈʤɛstɪd

risk-adjusted

Meaning
Modified or calibrated to account for risk factors in investment returns.
Example
Risk-adjusted returns consider both potential profit and loss.
B1 noun rɪˈflɛkʃən

reflection

Meaning
Serious thought or consideration about something.
Example
The reflection of the past filled his heart with sadness.
A2 noun /ruːf/

roof

Meaning
the top covering of a building or vehicle
Example
The roof of the house needs to be repaired.
C2 adjective /ˈræfɪʃ/

raffish

Meaning
unconventional and slightly disreputable but attractive
Example
He had a raffish charm that made him popular in the city.
C1 adjective /ˈruːfəl/

rueful

Meaning
Expressing sorrow, regret, or pity.
Example
He gave a rueful smile after losing the match.
A2 verb /riːtʃ/

reach

Meaning
to arrive at a destination; to extend one's arm to touch something
Example
We will reach the station in ten minutes.
B1 noun /ˈrʌnər/

runner

Meaning
a person who runs, especially in races or for exercise
Example
The runner crossed the finish line with a big smile.
C1 noun /ˈrem.nənt/

Remnant

Meaning
a small remaining quantity of something; a piece of cloth left over after the main piece has been used
Example
Only a remnant of the ancient wall remains.
C2 verb /rɪˈspaɪər/

respire

Meaning
To breathe in and out; to inhale and exhale.
Example
Plants also respire to release energy.
B2 adjective rɪˈnaʊnd

renowned

Meaning
Known or talked about by many people; famous.
Example
The renowned scientist led the reform panel.
B2 noun /ˈrɛlɪvənsi/

relevancy

Meaning
the quality of being closely connected or appropriate
Example
The professor questioned the relevancy of the example to the topic.
B2 verb /riːp/

reap

Meaning
to cut or gather a crop; to receive as a consequence of actions
Example
Farmers reap wheat in the late summer.
C1 phrase ˈriː.dʒən.əl ˈfɔː.rəm

regional forum

Meaning
A meeting or conference where representatives from countries or organizations in a specific geographical area discuss issues of common interest.
Example
The Regional Forum discussed deforestation impacts.
B1 adjective /roʊˈmæn.tɪk/

Romantic

Meaning
relating to love; idealistic; dreamy
Example
They enjoyed a romantic dinner by candlelight.
B1 verb /rɪˈkʌvər/

recover

Meaning
To return to a normal state of health, mind, or strength; to regain or save something.
Example
The world is struggling to recover from the pandemic.
C1 noun /ˌres.ɪˈteɪ.ʃən/

Recitation

Meaning
the action of reciting or repeating aloud from memory
Example
The poetry recitation contest was held in the auditorium.
C2 noun /ˈrɪp.lɪt/

ripplet

Meaning
a small or tiny ripple
Example
Tiny ripplets appeared on the lake as the fish moved.
A2 noun /ˈruːlər/

ruler

Meaning
A person who governs or controls a country; a straight-edged tool used for measuring or drawing lines
Example
The ruler drew a straight line on the paper while the king was a powerful ruler of his kingdom.
C2 verb /ˈrʌmpəl/

rumple

Meaning
to make something untidy or wrinkled by creasing or crumpling
Example
She accidentally rumpled her dress while packing.
C1 noun /rɪˈmɔːrs/

Remorse

Meaning
deep regret or guilt for a wrong committed; bitter regret for something done
Example
He felt deep remorse for his actions.
A2 adjective /ˈreɪ.ni/

Rainy

Meaning
characterized by rain; wet from rain; having much rain
Example
It was a rainy day, so we stayed indoors.
B2 verb /ˌriː.ɪnˈfɔːrs/

reinforce

Meaning
To strengthen or support something with additional material, people, or effort.
Example
The teacher used examples to reinforce the lesson.
C2 adjective /rəˈpeɪ.ʃəs/

rapacious

Meaning
having an extreme desire to take things for oneself, greedy
Example
The rapacious landlord raised the rent without reason.
B2 noun /ˈrɔɪəlti/

royalty

Meaning
Members of a royal family or payment made to the owner of a patent, copyright, or natural resource.
Example
The author receives a royalty for every book sold.
A1 adjective /red/

Red

Meaning
having the color of blood or fire; of the color red
Example
She wore a beautiful red dress to the party.
C1 verb /ˌriː.ɪˈstæblɪʃ/

reestablish

Meaning
to set up or restore something again after it has been disrupted
Example
The government worked hard to reestablish peace in the region.
C1 verb /rɪˈpjuː.di.eɪt/

repudiate

Meaning
to refuse to accept, recognize, or support something
Example
He repudiated the claim that he was involved in the scandal.
C2 noun /ˈrɛdʒɪsaɪd/

regicide

Meaning
the act of killing a king
Example
The conspirators were executed for committing regicide.
C2 noun /rɪˈsɪʒən/

rescission

Meaning
the cancellation or annulment of a law, contract, or agreement
Example
The rescission of the contract left both parties disappointed.
C2 verb /raɪv/

rive

Meaning
to tear apart violently
Example
The earthquake rived the ground in several places.
C1 noun /ˌrɛfjʊˈteɪʃən/

refutation

Meaning
The act of proving a statement or argument to be false or incorrect.
Example
Her essay was a strong refutation of the opposing theory.
C2 adjective /ˈruːbɪkənd/

rubicund

Meaning
Having a healthy reddish complexion.
Example
The old man’s rubicund face showed he was in good health.
C1 verb /riːˈpeɪ.tri.eɪt/

repatriate

Meaning
To return someone to their own country, often after war or imprisonment.
Example
The government worked to repatriate the refugees safely.