a grayish-white element having a metallic luster, vaporizing when heated, and forming poisonous compounds. Symbol:As; atomic weight:74.92; atomic number:33.
of or containing arsenic, esp. in the pentavalent state.
[Origin: 1350–1400; ME arsenicum < L < Gk arsenikón orpiment, n. use of neut. of arsenikós virile (ársén male, strong + -ikos-ic), prob. alter. of Oriental word (perh. < *arznig, metathetic var. of Syriac zarnig) by folk etym.]
Symbol As A highly poisonous metallic element having three allotropic forms, yellow, black, and gray, of which the brittle, crystalline gray is the most common. Arsenic and its compounds are used in insecticides, weed killers, solid-state doping agents, 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. See Table at element.
Arsenic trioxide.
adj.
ar·sen·ic (är-sěn'ĭk)
Of or containing arsenic, especially with valence 5.
[Middle English arsenik, from Old French, from Latin arsenicum, from Greek arsenikon, yellow orpiment, alteration of Syriac zarnīkā, from Middle Persian *zarnīk, from Old Iranian *zarna-, golden; see ghel-2 in Indo-European roots.]
c.1386, from O.Fr. arsenic, from L. arsenicum, from Gk. arsenikon "arsenic," adopted for Syriac (al) zarniqa "arsenic," from Middle Persian zarnik "gold-colored" (arsenic trisulphide has a lemon-yellow color). The Gk. word is folk etymology, from arsen "male, strong, virile" (cf. arseno-koites "lying with men" in N.T.) supposedly in reference to the powerful properties of the substance. The mineral (as opposed to the element) is properly orpiment, from L. auri pigmentum, so called because it was used to make golden dyes.
a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer
2.
a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar
arsenicAudio Help (är'sə-nĭk) Pronunciation Key Symbol As
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. See Periodic Table.
Ar"se*nic\ ([aum]r"s[-e]*n[i^]k; 277), n. [L. arsenicum, Gr. 'arseniko`n, 'arreniko`n, yellow orpiment, perh. fr. 'arseniko`s or better Attic 'arreniko`s masculine, 'a`rrhn male, on account of its strength, or fr. Per. zern[=i]kh: cf. F. arsenic.]1. (Chem.) One of the elements, a solid substance resembling a metal in its physical properties, but in its chemical relations ranking with the nonmetals. It is of a steel-gray color and brilliant luster, though usually dull from tarnish. It is very brittle, and sublimes at 356[deg] Fahrenheit. It is sometimes found native, but usually combined with silver, cobalt, nickel, iron, antimony, or sulphur. Orpiment and realgar are two of its sulphur compounds, the first of which is the true arsenicum of the ancients. The element and its compounds are active poisons. Specific gravity from 5.7 to 5.9. Atomic weight 75. Symbol As. 2. (Com.) Arsenious oxide or arsenious anhydride; -- called also arsenious acid, white arsenic, and ratsbane.
Ar*sen"ic\, a. (Chem.) Pertaining to, or derived from, arsenic; -- said of those compounds of arsenic in which this element has its highest equivalence; as, arsenic acid.
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Audio Help [n. ahr-suh-nik, ahrs-nik; adj. ahr-sen-ik] Pronunciation Key 
