English vocabulary · C1
Deleterious
/ˌdel.ɪˈtɪr.i.əs/ · adj.
It means causing serious harm, especially slowly over time. Something deleterious does not hurt you right away — it damages you little by little.
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Example sentences
- Smoking has a deleterious effect on your lungs.
- Too much screen time can be deleterious to children's sleep.
Word origin and roots
from Latin
- del — destroy (from Latin)
Synonyms and nuances
- HARMFUL — causing damage or hurt (General & Everyday)
- TOXIC — poisonous or very dangerous (Chemical & Intense)
- DAMAGING — causing lasting negative effects (Result-Focused)
Words with the same root
del — destroy
- delete — to remove or wipe out
- indelible — impossible to remove or forget
- deletion — the act of removing something
Lesson notes
Deleterious. It means causing serious harm, especially slowly over time. Something deleterious does not hurt you right away — it damages you little by little.
Similar words are harmful, toxic, and damaging. Use deleterious when something causes slow and serious harm to health or well-being.
Smoking has a deleterious effect on your lungs. Too much screen time can be deleterious to children's sleep.
From Latin. del- means destroy. Something that slowly destroys your health from the inside — that is deleterious.