# deleterious

Pronunciation: US/AUS say "del-uh-TEER-ee-uhs" /ˌdɛ.ləˈtɪɹ.i.əs/; UK say "del-i-TEER-ee-uhs" /ˌdɛl.ɪˈtɪə̯.ɹi.əs/

## Adjective

1. Causing harm or damage, often gradually or in ways not at first obvious; in genetics, lowering an organism's fitness.
   - Simple: Harmful, often in a slow or hidden way.
   - _Researchers found that long hours of screen time had a deleterious effect on children's sleep._
   - _Even low levels of the chemical may prove deleterious to fish in the river._

## Origin

The Greek root is dēléomai, meaning "I hurt, damage, spoil, waste." From it came dēlētḗr ("a destroyer") and then dēlētḗrios ("noxious, deleterious"). New Latin took this as dēlētērius or dēlētōrius, and English adapted it with -ous in the 1640s, after an earlier form deletorious in 1582. Despite appearances it is not related to delete, but it is a doublet of deletery.

Source: DictionaryAI, https://dictionaryai.com/define/deleterious (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).