Deleterious
/ˌdɛlɪˈtɪriəs/
adjectiveC1
Definition
Deleterious describes something that causes harm or damage to a person, thing, or situation. It often refers to effects that are bad for health, the environment, or well-being. The word is usually used in formal or scientific contexts.
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See It in Action
Causing harm or damage, especially to health or the environment
- •Smoking has deleterious effects on the lungs.
- •Pollution can have deleterious impacts on wildlife.
- •The drug had deleterious side effects that worried the doctors.
Harmful in a general or figurative sense
- •His negative attitude was deleterious to the team's spirit.
- •Cutting corners in work can be deleterious to the company's reputation.
Make It Stick
- ✓Think of "deleterious" like "bad," but more serious and often about health or safety
- ✓Picture a plant slowly dying because of harmful chemicals in the soil
- ✓It's the feeling when something causes trouble or pain without you wanting it
- ✓Sounds like "delete" + "serious" → imagine something seriously deleting or removing good parts, causing harm
- ✓Think of a story where a character eats poisonous food that slowly hurts them
- ✓NOT like "bad" (general and simple), "deleterious" means specifically harmful or damaging, often in a lasting way
- ✓NOT like "dangerous" (immediate risk), "deleterious" can be slow or hidden harm
- ✓NOT like "unpleasant" (just not nice), "deleterious" means causing real damage or injury
Try Other Words
- •Harmful: causing damage or injury (Use when talking about general or everyday harm)
- •Damaging: causing damage (Use when focusing on physical or emotional damage)
- •Injurious: causing injury or harm (Use in formal or legal contexts)
- •Toxic: poisonous or very harmful (Use when harm is from poison or chemicals)
Unboxing
- •Word parts: "de-" (down, away) + "leter" (from Greek "letos" meaning harm) + "-ious" (adjective ending)
- •Etymology: From Greek "dēlēterios," meaning "noxious" or "destructive"
- •Historical development: Entered English in the 17th century, used mainly in scientific or formal writing to describe harmful effects
- •Modern usage: Common in medicine, science, and formal writing to describe things that cause damage or harm
Reflect & Connect
•Can something be harmful but not deleterious? How do you tell the difference?
•How might understanding the word deleterious help you make better choices about your health or environment?
Fill in the blanks
1.Long-term exposure to chemicals can have deleterious ___ on human health and the environment.
2.His careless actions were deleterious ___ the success of the project.
3.Unlike a sudden accident, deleterious effects often happen ___ over time.
4.The company ignored the deleterious ___ of pollution on local wildlife.
5.Smoking is known to have deleterious ___ on the lungs and heart.
6.The manager warned that negative comments could be deleterious ___ team morale.
7.Sometimes, deleterious ___ are not easy to see immediately but become clear later.