radioactive
gb/ɹˌeɪdioʊˈæktɪv/ us/ɹˌeɪdioʊˈæktɪv/
B2
英語
~ 5800
語義
0件の語義
adjective
technical
B2
property
1
emitting harmful ionizing radiation
Giving off a kind of invisible energy, called radiation, because its atoms are not stable.
用法パターン：
radioactive [substance/material/waste/isotope]
よくある間違い：
Learners sometimes use "radioactive" when they only mean "radio" or "nuclear" in a general sense (for example, saying *"a radioactive station"* instead of *"a radio station"*). "Radioactive" should only be used when something actually emits ionizing radiation.
類義語
radioactive-contaminated (Emphasizes that a substance has been made radioactive by exposure, rather than being naturally radioactive.)
|
nuclear (Often used informally for things involving radiation, but more broadly refers to atomic energy or weapons, not always literally emitting radiation.)
|
unstable (In physics, describes atomic nuclei that will decay and emit radiation; more general and less explicit about radiation itself.)
対義語
non-radioactive (Direct opposite; clearly states that something does not emit ionizing radiation.)
|
stable (In nuclear physics, describes nuclei that do not decay and therefore do not emit radiation.)
コロケーション
radioactive waste
|radioactive material
|highly radioactive
|radioactive decay
|radioactive contamination
|radioactive isotope
テーマ
science
|health
|environment
例文
- Workers must wear protective clothing when handling highly radioactive waste.
- The accident released radioactive material into the surrounding area.
- Iodine-131 is a radioactive isotope commonly used in medical tests.
- Scientists measured the radioactive decay of the sample to estimate its age.
- The leak caused radioactive contamination of the soil and groundwater.
学習者向け例文
- This area is dangerous because the ground is radioactive.
- They store the radioactive waste deep underground.
- The lab keeps all radioactive material in special containers.
- The doctor used a small amount of a radioactive substance in the test.
- Radioactive dust can be very bad for your health.
adjective
informal
C1
property
2
socially or politically untouchable
Very risky to be close to or support, because many people strongly dislike it or it may cause serious trouble.
用法パターン：
radioactive [topic/issue/brand/person]
よくある間違い：
Learners may think this meaning is literal and expect some connection to physical radiation. In this sense, "radioactive" is only metaphorical and describes social or political risk, not actual physical danger.
類義語
toxic (Very common metaphor; can describe people, relationships, or topics that cause harm or trouble.)
|
untouchable (Focuses on the idea that people refuse any contact or support.)
|
taboo (Emphasizes that something should not be talked about or done, often for social or moral reasons.)
対義語
safe (Suggests that talking about or being connected with something will not cause problems.)
|
uncontroversial (Highlights that most people agree about it, so it does not create conflict.)
コロケーション
politically radioactive
|radioactive topic
|radioactive issue
|radioactive brand
|radioactive name
テーマ
politics
|relationships
|business
例文
- After the scandal, his name became politically radioactive.
- The brand was so radioactive that no major retailer wanted to stock its products.
- Immigration has turned into a radioactive issue in the campaign.
- The memo was considered radioactive, and nobody wanted to be copied on it.
- That topic is practically radioactive in this company; people just won’t discuss it publicly.
学習者向け例文
- After the news story, the company became radioactive and lost many customers.
- This is a radioactive topic, so people do not talk about it at work.
- The politician is now radioactive; no one wants to work with him.
- The movie star’s image was radioactive after the big scandal.
- That idea is too radioactive for the team to support.
文法
辞書形
radioactive
IPA
GB/ɹˌeɪdioʊˈæktɪv/
US/ɹˌeɪdioʊˈæktɪv/
音節・強勢
ra - dio - act - ive （4音節）
Stress on 3rd syllable (act)
活用形
Adjective
- Base: radioactive
関連語
表現
radioactive contamination
1/ɹˌeɪdioʊˈæktɪv kəntˌæmənˈeɪʃən/
fixed phrase
technical
unwanted spread of radioactive substances
When radioactive material gets onto land, water, air, or objects where it should not be.
例文
- The accident caused widespread radioactive contamination of farmland.
- They tested the area for radioactive contamination before letting residents return home.
- Protective clothing helps prevent radioactive contamination of workers’ skin and clothes.
radioactive fallout
1/ɹˌeɪdioʊˈæktɪv fˈɔlˌaʊt/
fixed phrase
technical
radioactive particles falling after an event
Dust and small pieces of radioactive material that fall from the sky to the ground after a nuclear blast or accident.
例文
- People were advised to stay indoors to avoid radioactive fallout.
- The radioactive fallout spread across several neighboring countries.
- Maps showed the direction of the radioactive fallout cloud after the explosion.
radioactive material
1/ɹˌeɪdioʊˈæktɪv mətˈɪɹiəl/
fixed phrase
technical
substance that emits radiation
Any solid, liquid, or gas that gives off ionizing radiation.
例文
- Only trained staff are allowed to handle radioactive material in the laboratory.
- The shipment of radioactive material was escorted by police for safety reasons.
- They detected traces of radioactive material in the river water after the leak.
radioactive poisoning
1/ɹˌeɪdioʊˈæktɪv pˈɔɪzənɪŋ/
fixed phrase
technical
illness from too much radiation
Serious sickness that happens when a person is exposed to too much radiation from radioactive material.
例文
- The workers showed signs of radioactive poisoning after the incident.
- Doctors treated several patients for suspected radioactive poisoning.
- High doses of radiation can cause radioactive poisoning and even death.
radioactive waste
1/ɹˌeɪdioʊˈæktɪv wˈeɪst/
fixed phrase
technical
hazardous waste that emits radiation
Waste material from nuclear work that gives off dangerous radiation and must be stored very carefully.
例文
- The government is searching for a long-term storage site for radioactive waste.
- Radioactive waste must be kept in secure containers for thousands of years.
- Protesters gathered outside the plant to oppose the transport of radioactive waste through their town.
radioactive decay
1/ɹˌeɪdioʊˈæktɪv dɪkˈeɪ/
fixed phrase
technical
process of unstable nuclei breaking down
The process in which unstable atoms slowly change into other atoms and give off radiation.
例文
- The rate of radioactive decay is described by the half-life.
- Scientists use the rate of radioactive decay to date ancient objects.
- Radioactive decay releases energy in the form of particles and radiation.
- Radioactive decay produces heat inside the Earth’s core.
- Scientists measured the radioactive decay of carbon to date the artifact.
- The chart shows how radioactive decay reduces the activity of the sample over time.