\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.