arsenic

1 of 2

noun

ar·​se·​nic

ˈärs-nik,

ˈär-sə- 

1

: a solid chemical element that is used especially in wood preservatives, alloys, and semiconductors and is extremely toxic in both pure and combined forms see Chemical Elements Table

2

: a poisonous trioxide As₂O₃ or As₄O₆ of arsenic used especially as an insecticide or weed killer

called also arsenic trioxide

arsenic

2 of 2

adjective

ar·​sen·​ic är-ˈse-nik 

: of, relating to, or containing arsenic especially with a valence of five

Examples of arsenic in a Sentence

Recent Examples on the Web

Noun

The naturally occurring background level of arsenic in Altadena and Pasadena ranges from 4 to 10 mg/kg, according to a 2019 study by the U.S. Geological Survey. —Noah Haggerty, Los Angeles Times, 16 May 2025

In fact, it’s been clear for many years that arsenic accumulates most in rice’s outer bran layer. —Sarah Garone, Health, 29 Apr. 2025

Adjective

The more stringent standards effectively limit emissions of other toxics, including benzene, lead and arsenic. —Michael Hawthorne, Chicago Tribune, 25 May 2025

Some research suggests that climate change could also be causing higher levels of arsenic in rice. —The Washington Post, San Diego Union-Tribune, 6 May 2025

Word History

Etymology

Noun

Middle English arsenek, arsenic "any of various compounds of arsenic, as yellow orpiment (arsenic trisulfide)," borrowed from Anglo-French & Latin; Anglo-French arsenik, arsneke, borrowed from Latin arrhenicum, arsenicon, borrowed from Greek arsenikón, arrhenikón, probably borrowed from Aramaic zarnīḵ "arsenic" or a cognate Semitic word, borrowed from an unattested form in a Middle Iranian language (whence Persian zarnī, zarnīk "orpiment, arsenic"), a derivative of the word for "gold" (as Manichaean Parthian zrn /zarn/ "gold," zrnyn /zarnēn/ "golden"), alluding to the yellow color of orpiment

Note: The Greek word is assumed to have been reshaped by folk-etymological association with arsenikós, arrhenikós "male, masculine." Aramaic zarnīḵ is attested in a papyrus text (an order to repair a boat) dated January, 411 b.c., found in elephantine, Egypt (see A. Cowley, Aramaic Papyri of the Fifth Century B.C., Oxford, 1923, pp. 88-97; B. Porten, The Elephantine Papyri in English: Three Millennia of Cross-Cultural Continuity and Change, Brill, 1996, pp. 115-22); the word is also attested in Syriac a number of centuries later. The Manichaean Parthian forms are from D. Durkin-Meisterernst, Dictionary of Manichaean Texts, vol. III, Part 1, Dictionary of Manichaean Middle Persian and Parthian, Brepols, 2004. Parthian zrn and zrnyn are continuations of an Old Iranian etymon represented by Avestan zarańiia- "gold"—see note at gold entry 1.

Adjective

from attributive or compound use of arsenic entry 1

First Known Use

Noun

1747, in the meaning defined at sense 1

Adjective

1798, in the meaning defined above

Kids Definition

arsenic

noun

ar·​se·​nic

ˈärs-nik,

-ᵊn-ik

1

: a solid poisonous element that is commonly metallic steel-gray and brittle see element

2

: a white or transparent extremely poisonous oxide of arsenic used especially in insecticides

Medical Definition

arsenic

1 of 2 noun

ar·​se·​nic ˈärs-nik, -ᵊn-ik 

1

: a trivalent and pentavalent solid poisonous element that is commonly metallic steel-gray, crystalline, and brittle

—symbol As see Chemical Elements Table

2

: arsenic trioxide

arsenic

2 of 2 adjective

ar·​sen·​ic är-ˈsen-ik 

: of, relating to, or containing arsenic especially with a valence of five