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.

---

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

---

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

---

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

A garlicky smell once alerted him to the presence of arsenic in sugar, while the spill of a concentrated solution cut through clothing “like the blow of a scimitar.”

From The Wall Street Journal ● Aug. 24, 2026

Scientists found cyanide, arsenic and PCBs at the site and said it needed to be cleaned up, he said.

From BBC ● Aug. 10, 2026

In 2015, a battery recycling plant that had been operating in Vernon for decades had to close down and pay $50 million toward cleaning up its hazardous wastes such as lead dust, cadmium and arsenic.

From Los Angeles Times ● Jul. 15, 2026

Researchers from the University of Cambridge's Department of Zoology collected pollen using pollen traps and measured levels of arsenic, cadmium, chromium, cobalt, lead, and tin in both pollen and adult bees.

From Science Daily ● Jul. 7, 2026

If a highly poisonous herbicide such as arsenic has been used, this intense desire to reach the wilting vegetation inevitably has disastrous results.

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 M. M. Pattison (Matthew Moncrieff Pattison) Muir