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pal·la·di·um 1 (pə-lādē-əm)
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n. Symbol Pd
A soft, ductile, lustrous gray-white, tarnish-resistant, metallic element occurring naturally with platinum, especially in gold, nickel, and copper ores. Because it can absorb large amounts of hydrogen, it is used as a purification filter for hydrogen and a catalyst in hydrogenation. It is alloyed for use in electric contacts, jewelry, nonmagnetic watch parts, and surgical instruments. Atomic number 46; atomic weight 106.4; melting point 1,554.8°C; boiling point 2,963°C; specific gravity 12.02 (20°C); valence 2, 3, 4. See Periodic Table.

[From PALLAS (discovered at the same time as the element).]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 
pal·la·di·um 2 (pə-lādē-əm)
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n. pl. pal·la·di·a (-dē-ə) or pal·la·di·ums
1. A safeguard, especially one viewed as a guarantee of the integrity of social institutions: the Bill of Rights, palladium of American civil liberties.
2. A sacred object that was believed to have the power to preserve a city or state possessing it.

[Middle English Palladion, a statue of Pallas Athena believed to protect Troy, from Old French palladion, from Latin Palladium, from Greek Palladion, from Pallas, Pallad-, Pallas Athena.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

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:

    Indo-European Roots

    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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