noun \ˈärs-nik, ˈär-sə-\

: a poisonous chemical that is used especially to kill insects and weeds

Full Definition of ARSENIC

:  a trivalent and pentavalent metalloid poisonous element that is commonly metallic steel gray, crystalline, and brittle and is used especially in wood preservatives, alloys, and semiconductors — see element table
:  a poisonous trioxide As2O3 or As4O6 of arsenic used especially as an insecticide or weed killer —called also arsenic trioxide

Origin of ARSENIC

Middle English arsenik orpiment, from Anglo-French & Latin; Anglo-French, from Latin arsenicum, from Greek arsenikon, arrhenikon, from Syriac zarnīg, of Iranian origin; akin to Avestan zaranya gold, Sanskrit hari yellowish — more at yellow
First Known Use: 14th century


adjective \är-ˈse-nik\

Definition of ARSENIC

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

First Known Use of ARSENIC



noun    (Concise Encyclopedia)

Arsenic (gray) with realgar (red) and orpiment (yellow)—Courtesy of the Joseph and Helen Guetterman collection; photograph, John H. Gerard

Nonmetallic to semimetallic chemical element, chemical symbol As, atomic number 33. It exists uncombined in two stable (and several unstable) allotropes, one gray and one yellow, but is more often found in nature as the sulfide or oxide. The elemental form is used to form alloys of metals (especially lead), and certain semiconductors are made from crystals of gallium arsenide (GaAs). Arsenious oxide (arsenic trioxide or white arsenic, AsO) is used in pesticides, as a pigment, and as a preservative of hides and wood; this is the poisonous “arsenic” (see arsenic poisoning) in detective stories. Arsenic pentoxide (AsO) is also used in insecticides, herbicides, metal adhesives, and pigments.


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