arsenic

American  

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

noun

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

• nonarsenic adjective

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”; 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

One prominent enthusiast had 40,000 skins, almost certainly preserved with arsenic.

From The Wall Street Journal • Mar. 23, 2026

Physicians say trace amounts of substances such as arsenic are commonly found in many foods, and stricter FDA limits introduced in 2023 make products more likely to be flagged as elevated today.

From The Wall Street Journal • Feb. 17, 2026

Although lead is one of the most common and dangerous contaminants left behind after fires, federal and state disaster officials have traditionally tested soil for 17 toxic metals, including cancer-causing arsenic and toxic mercury.

From Los Angeles Times • Jan. 12, 2026

He's laboratory focuses on how environmental stressors, including UV radiation and arsenic in drinking water, disrupt molecular pathways and damage cellular systems in ways that promote cancer.

From Science Daily • Nov. 30, 2025

Drifting arsenic dusts from blueberry lands have spread over neighboring farms, contaminating streams, fatally poisoning bees and cows, and causing human illness.

From "Silent Spring" by Rachel Carson