Noxious vs obnoxious

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Noxious and obnoxious are two words that are sometimes confused. Though they contain the same Latin root, these words have different meanings. We will examine the definitions of noxious and obnoxious, where these two words came from and some example so their use in sentences.

Noxious describes something that may injure, something harmful, something that is poisonous. Noxious is sometimes used to describe something that is very unpleasant, but in that case it is a metaphor for its true definition. Synonyms for noxious that may be found in a thesaurus are toxic, poisonous, unhealthy, detrimental. A noxious weed is one that has been designated harmful to agriculture, livestock, humans or an ecosystem. A noxious weed may be an invasive species or a native species. In the United States, the federal government maintains a list of designated noxious weeds, as does each state. Some wild plants that have been noxious weeds in the United States are purple loosestrife, kudzu, hydrilla and hogweed. The adjective noxious is often used to describe a poison or a deadly gas. Noxious describes something that may harm one’s health. The adverb form is noxiously and the noun form is noxiousness. The word noxious is derived from the Latin word noxa, which means injury or harm.

Obnoxious describes that is extremely unpleasant, insulting, or annoying. Obnoxious is usually used to describe a person whose behavior is extremely unpleasant, insulting or annoying. Synonyms for obnoxious that may be found in a thesaurus are repulsive, objectionable, disagreeable and loathsome. The adjective obnoxious is often used to describe a bratty child or a loud, annoying person. Obnoxious describes someone who is unpleasant to be around. The adverb form is obnoxiously and the noun form is obnoxiousness. The word obnoxious is derived from the Latin word noxa, meaning injury or harm, and the prefix ob-, which means toward. Remember, noxious and obnoxious may be used to describe the same thing, but the meanings are different. For example, a noxious odor is one that may burn one’s lungs or harm one’s health in some manner. An obnoxious odor is simply a foul smell that causes discomfort, but does not affect one’s health.


A number of people were also sprayed with a noxious substance during the violence. (The Independent)

Weeds and controlling them were the subject of a day of continuing education classes Wednesday at the 22nd Annual Noxious Weed Conference. (The Columbia Basin Herald)

By means of time-lapse in vivo calcium imaging and neural activity manipulation in freely behaving mice encountering noxious stimuli, we identified a distinct neural ensemble in the basolateral amygdala that encodes the negative affective valence of pain. (Science Magazine)

Obnoxiously loud subway-gate alarms are returning to some stations as part of a pilot program to stop farebeaters, according to transit officials. (The New York Post)

Cubs fans also may recall when the elder Brennaman called them in April 2008 “far and away the most obnoxious fans in baseball in this league.” (The Chicago Tribune)

Filling out the rest of the stellar cast of The Upside are Aja Naomi King who plays Latrice, Dell’s ex-girlfriend and the mother of his child, Suzanne Savoy as Charlotte, Phillip’s long-time chef, Julianna Margulies, a pen pal Phillip finally gets the courage to meet for a date, Tate Donovan, the wealthy and somewhat obnoxious budding art collector living in Phillip’s building, and Genevieve Angelson, as Phillip’s deceased wife, Jenny. (The Manila Standard)