arsenic

American  

[ahr-suh-nik, ahrs-nik, ahr-sen-ik] / ˈɑr sə nɪk, ˈɑrs nɪk, ɑrˈsɛn ɪk /

noun

arsenics plural

1. a grayish-white element having a metallic luster, vaporizing when heated, and forming poisonous compounds. As; 74.92; 33.

2. arsenic trioxide.

3. a mineral, the native element, occurring in white or gray masses.

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adjective

1. of or containing arsenic, especially in the pentavalent state.

arsenic British  

noun

1. a toxic metalloid element, existing in several allotropic forms, that occurs principally in realgar and orpiment and as the free element. It is used in transistors, lead-based alloys, and high-temperature brasses. Symbol: As; atomic no: 33; atomic wt: 74.92159; valency: –3, 0, +3, or +5; relative density: 5.73 (grey); melting pt: 817°C at a pressure of 3MN/m² (grey); sublimes at 613°C (grey)

2. a nontechnical name for arsenic trioxide

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adjective

1. of or containing arsenic, esp in the pentavalent state

arsenic Scientific  

/ är′sə-nĭk /

1. A metalloid element most commonly occurring as a gray crystal, but also found as a yellow crystal and in other forms. Arsenic and its compounds are highly poisonous and are used to make insecticides, weed killers, and various alloys. Atomic number 33; atomic weight 74.922; valence 3, 5. Gray arsenic melts at 817°C (at 28 atm pressure), sublimes at 613°C, and has a specific gravity of 5.73.

2. See Periodic Table

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Other Word Forms

Derived Forms

• nonarsenic
  adjective

Inflected Forms

Nouns

• arsenics
  plural

Etymology

Origin of arsenic

First recorded in 1350–1400; Middle English arsenicum, from Latin, from Greek arsenikón “orpiment” (a mineral), noun use of neuter of arsenikós “virile” (from ársēn “male, strong” + -ikos -ic ), probably alteration by folk etymology of a Semitic word such as Syriac zarnīkā “orpiment,” from Middle Persian (compare Persian zargūn “gold-colored”; see jargon ² ( def. ))

Explanation

Arsenic is a chemical element that's quite poisonous to humans and other animals. Arsenic was once commonly used in rat poison and insecticides. While arsenic is a naturally occurring element, it's often thought of as a poison used in mystery novels to murder people. Several kinds of agricultural bug killers once contained arsenic, but historically people have been more likely to suffer arsenic poisoning from natural leaching into water sources, like wells, or as a side effect of mining. Arsenic has a Greek root, arsenikon, from the Middle Persian zarnik, "gold colored."

Example Sentences

See Examples For:

arsenic arsenics

Residents can collect soil samples and deliver them to Boyle Heights City Hall and other locations for an evaluation of lead, arsenic, chromium and mercury levels.

From Los Angeles Times ● Jul. 8, 2026

Implementing the updated rule would “reduce emissions of toxic metals, primarily lead and arsenic, by nearly 50 percent” at the country’s several copper smelters, the EPA concluded.

From Salon ● May 10, 2026

Producing rare earths requires heavy chemicals and can produce toxic waste, with cases including illegal operations polluting Mekong tributaries in Myanmar, Laos and Cambodia with arsenic and cadmium.

From Barron's ● Apr. 22, 2026

A Consumer Reports review of 41 types of powdered infant formula last year found that about half contained detectable levels of contaminants such as arsenic, lead and “forever chemicals” known as PFAS.

From The Wall Street Journal ● Feb. 17, 2026

The underground water also became contaminated, and arsenic entered the drinking water.

From "Silent Spring" by Rachel Carson

The life of metals is a secret fatness; of salts, the spirit of aqua fortis; of pearls, their splendour; of marcasites and antimony, a tingeing metalline spirit; of arsenics, a mineral and coagulated poison.

From Heroes of Science Chemists by Muir, M. M. Pattison (Matthew Moncrieff Pattison)