Harmful
Harmful adjective - Causing or capable of causing harm.
Usage example: DDT has been proven to be extremely harmful to the environment
Noxious is a synonym for harmful in health topic. In some cases you can use "Noxious" instead an adjective "Harmful", when it comes to topics like injurious, pernicious, adverse, deleterious. popular alternative
Noxious
Noxious adjective - Causing or capable of causing harm.
Usage example: noxious smog that for years has been encrusting the historic cathedral with soot
Harmful is a synonym for noxious in health topic. You can use "Harmful" instead an adjective "Noxious", if it concerns topics such as pernicious, adverse, deadly, deleterious. popular alternative
Nearby Words: noxiousness, noxiously
Mutual synonyms
Both words in one sentence
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Kill All Humans: Humans are "destructive, invasive, noxious, harmful to the body of the whole".
Source: Film / Virus
Cite this Source
Noxious and Harmful. (2016). Retrieved 2026, August 15, from https://thesaurus.plus/related/harmful/noxious
Harmful & Noxious. N.p., 2016. Web. 15 Aug. 2026. <https://thesaurus.plus/related/harmful/noxious>.
Noxious or Harmful. 2016. Accessed August 15, 2026. https://thesaurus.plus/related/harmful/noxious.
Google Ngram Viewer shows how "harmful" and "noxious" have occurred on timeline