Word
poisonous
Phoneticspoi·sonous
US/ˈpɔɪzənəs/
UK/pˈɔɪzənəs/
Definitions
01dangerous to eat or touch
B1 · Intermediate
adj. describes something that contains a substance that can cause illness or death if it enters your body.
adj. containing or producing a substance that causes injury, illness, or death when absorbed or ingested.
“Be careful not to eat those berries because they are poisonous.”
“The bright colours of certain tropical frogs serve as a warning to predators that their skin is highly poisonous.”
Usage
Often used with 'to' to indicate who is at risk, such as 'poisonous to humans'.
Pitfall
The snake is poisonous.
The snake is venomous.
In technical English, 'poisonous' means it hurts you if you eat it; 'venomous' means it hurts you if it bites you. However, many people use 'poisonous' for both in casual speech.
02harmful or unpleasant
B2 · Upper Intermediate
adj. describes a person, feeling, or situation that is very negative and harmful to others.
adj. extremely unpleasant, malicious, or harmful in a figurative sense; often applied to social atmospheres or interpersonal relationships.
“He decided to leave the company because of the poisonous atmosphere in the office.”
“The politician's poisonous rhetoric served only to further divide the community during the election cycle.”
Teaching tip
This figurative sense is very common in modern workplace and relationship discussions, often interchangeable with 'toxic'.
Antonyms
Collocations
Common phrases and expressions where native English speakers use the word “poisonous” in context.
Verb
01. become poisonous
“The relationship became poisonous after they stopped trusting each other.”
verb + adj
Adjective
02. highly poisonous
“Be careful with those berries; they are highly poisonous if eaten.”
adv + adj
03. poisonous gas
“The old factory was closed because it was releasing poisonous gas into the air.”
adj + noun
04. poisonous snake
“The hikers were warned to watch out for a poisonous snake hidden in the tall grass.”
adj + noun
05. poisonous to humans
“Certain types of mushrooms are poisonous to humans but safe for some animals.”
adj + prep + noun
Noun
06. poisonous atmosphere at work
“The constant arguing created a poisonous atmosphere at work that made everyone unhappy.”
adj + noun + prep + noun
Etymology
From Middle English poisounous, poysonouse. By surface analysis, poison + -ous.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
NOUN
ADJECTIVE
Idioms
- 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.B1 PreliminaryIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.4.0–5.0TOEFL 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: 3.0–3.544–71TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.550–784
- Frequency
- Frequent
- Level
- B1 · IntermediateOxford
- Updated
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QR code
englishreference.com/q/poisonous