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DictionarydeleteriousHarmful
adjective

deleterious

del-uh-TEER-ee-us/ˌdeləˈtɪriəs/

Causing harm or damage.

The exhaust has a deleterious effect, making the woman cough and recoil.

A young woman recoils and coughs as thick exhaust from an idling vehicle drifts directly into her face, making the harmful effect of polluted air visible.
Etymology
deleteriousGreeknoxious, harmful

Greek dēlētērios, “noxious,” comes from a word meaning “destroyer,” ultimately tied to hurting or injuring. English first used the adjective for poisonous harm, then extended it to mental or moral injury.

In context

Modern-Day Debate14:03
zero percent of it is beneficial it's a hundred percent deleterious people have actually gotten injured and died from these phenomena
Is There Something to Alien Abductions? | Dr Hugh Ross Vs TJump

More examples

  • The chemical is deleterious to aquatic life.
  • Chronic stress can have a deleterious effect on sleep.
  • The report examines the deleterious consequences of cutting school funding.

Forms

deleterious · more deleterious · most deleterious

Similar words

harmful
The everyday alternative; deleterious sounds more formal or technical.
detrimental
Often emphasizes setbacks to interests or progress rather than physical damage.
injurious
Often emphasizes injury to health, reputation, or personal interests.