Deleterious

//ˌdɛl.ɪˈtɪə̯.ɹi.əs// adj

adj ·Moderate ·College level

Definitions

Adjective
  1. 1
    Harmful, often in a subtle or unexpected way. formal

    "deleterious effects"

  2. 2
    Having lower fitness.

    "A deleterious mutation"

Adjective
  1. 1
    harmful to living things wordnet

Synonyms

All synonyms
harmfulbadabandonedadversearrantbad

Example

More examples

"We cannot continue to ignore the deleterious effects of these policies on our country."

Etymology

Adapted borrowing (1640s; 1582 as deletorious) of New Latin dēlētērius, dēlētōrius + -ous, from Ancient Greek δηλητήριος (dēlētḗrios, “noxious, deleterious”), from δηλητήρ (dēlētḗr, “a destroyer”), from δηλέομαι (dēléomai, “I hurt, damage, spoil, waste”). Not related to delete or deleble. Doublet of deletery.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.