[ noun ahr-suh-nik, ahrs-nik; adjective ahr-sen-ik ]
/ noun ˈɑr sə nɪk, ˈɑrs nɪk; adjective ɑrˈsɛn ɪk /
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a grayish-white element having a metallic luster, vaporizing when heated, and forming poisonous compounds. Symbol: As; atomic weight: 74.92; atomic number: 33.
a mineral, the native element, occurring in white or gray masses.

adjective ar·sen·ic [ahr-sen-ik] /ɑrˈsɛn ɪk/

of or containing arsenic, especially in the pentavalent state.



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Origin of arsenic

1350–1400; Middle English arsenicum<Latin <Greek arsenikón orpiment, noun use of neuter of arsenikós virile (ársēn male, strong + -ikos-ic), probably alteration of Semitic word (perhaps <*arznig, metathetic variant of Syriac zarnig) by folk etymology
non·ar·sen·ic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for arsenic


noun (ˈɑːsnɪk)

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)
a nontechnical name for arsenic trioxide

adjective (ɑːˈsɛnɪk)

of or containing arsenic, esp in the pentavalent state
C14: from Latin arsenicum, from Greek arsenikon yellow orpiment, from Syriac zarnīg (influenced in form by Greek arsenikos virile)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for arsenic

[ ärsə-nĭk ]

n. Symbol As

A poisonous metallic element, compounds of which are used as antamebics. Atomic number 33.


Of or containing arsenic, especially with valence 5.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for arsenic

[ ärsə-nĭk ]


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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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