deleterious
/ˌdɛl.ɪˈtɪə.ri.əs/ IELTSAcademic
adjective
Causing harm or damage, especially in a slow or serious way. It is common in formal, academic, and medical writing.
- Smoking has deleterious effects on health.
- The policy had deleterious results.
- Poor sleep can be deleterious to learning.
Adinary Nuance
Deleterious is stronger and more formal than harmful. Use harmful in everyday English, and deleterious in academic, medical, or official writing. It often suggests damage that is serious, long-term, or not immediately visible.
In other languages
- Vietnamese
- có hại
- Spanish
- perjudicial
- Chinese
- 有害的
- Japanese
- 有害な
- Korean
- 해로운
Etymology
From Latin deleterius, meaning “destructive” or “harmful,” from the Greek root for “destroy.” It entered English in the 1600s and stayed mainly formal.
Common phrases
deleterious effectsdeleterious impactdeleterious to healthdeleterious consequences
Synonyms
Related words
Frequently asked questions
- Is deleterious formal or informal?
- It is formal. You will see it more in academic, scientific, and legal writing than in casual speech.
- What is the difference between deleterious and harmful?
- Both mean causing harm. **Deleterious** sounds more formal and often suggests deeper or longer-term damage.
- Can I use deleterious in IELTS Writing?
- Yes. It is a good choice for formal essays when you want a precise, academic tone.
- What preposition comes after deleterious?
- The most common pattern is **deleterious to** something, like **deleterious to health**.