Word
radioactive
Phoneticsra·dioac·tive
US/ˌɹeɪdioʊˈæktɪv/
UK/ɹˌeɪdɪəʊˈæktɪv/
Definitions
01emitting radiation
B2 · Upper Intermediate Science Technical
adj. sending out energy in the form of rays or particles that can be harmful to living things.
adj. exhibiting radioactivity through the spontaneous emission of ionising radiation from unstable atomic nuclei.
“The workers wore special suits to protect themselves from the radioactive waste.”
“The containment vessel was designed to withstand the intense heat and pressure generated by the radioactive decay of the spent fuel rods.”
Usage
Usually precedes the noun it modifies.
02dangerous or toxic
C1 · Advanced Informal
adj. so controversial, dangerous, or unpleasant that people want to avoid it completely.
adj. highly controversial or socially toxic; used figuratively to describe individuals or topics that are perceived as damaging to associate with.
“After the scandal, the politician became radioactive and no one wanted to work with him.”
“The proposed policy became politically radioactive after the leaked documents revealed the true cost to the taxpayers.”
Teaching tip
This is a common metaphorical use in business and politics to describe someone whose reputation is ruined.
Real-World Examples
“Any part of your body that contains carbon—which is every part of your body—is radioactive.” “They found that radioactive decay alone couldn't explain this behavior.” Etymology
Coined by Pierre Curie and Marie Curie in 1898 as French radio-actif, equivalent to English radio- + active.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
NOUN
ADJECTIVE
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
- Frequency
- Frequent
- Level
- B2 · Upper Intermediate
- Updated
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englishreference.com/q/radioactive