noxious

Noxious is an adjective used to describe something that is harmful or injurious to health, safety, property, or well-being. It can refer to physical substances, such as chemicals or gases, as well as to odors, wastes, or other factors that cause discomfort or risk. The word can also be applied metaphorically to ideas, influences, or behaviors judged to be harmful or pernicious.

Etymology and usage history: Noxious derives from Latin nocere, meaning to injure. The form noxious entered English through later Latin and French intermediaries and has been in use since the early modern period. It is a broad term, often chosen for emphasis beyond mere nuisance.

Common usage and collocations: Noxious fumes, noxious gas, and noxious odors are frequent descriptors in science, industry, and law. Noxious weeds refer to plant species deemed harmful to agriculture or ecosystems. The term can also describe morally or socially harmful influences, such as noxious ideas or conduct, though in everyday speech it usually conveys a strong negative assessment of harmfulness or offensiveness.

Noxious versus toxic or poisonous: Toxic or poisonous describes substances with a capacity to cause poisoning at sufficient exposure. Noxious emphasizes harmfulness more generally and may include irritation, nuisance, or health risks without implying a dose-dependent poisoning. In regulatory and environmental contexts, noxious is used to label substances, emissions, or organisms that pose health or ecological risks.

See also: harmful, poisonous, toxic, noxious weed, noxious odor.