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ar·se·nic

(ärsə-nĭk)

1. Symbol As A highly poisonous metallic element having several allotropic forms of which the brittle, crystalline gray metallic form is the most common. The less stable yellow allotrope has a molecular structure, As₄. Arsenic and its compounds are used in insecticides, weed killers, semiconductor dopants, and various alloys. Atomic number 33; atomic weight 74.9216; valence 3, 5. Gray arsenic melts at 817°C (at 28 atm pressure), sublimes at 616°C, and has a specific gravity of 5.75. See Periodic Table.

2. Arsenic trioxide.

adj. ar·sen·ic (är-sĕn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 the Appendix of Indo-European roots.]

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

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Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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