platinum
Chemistry. a heavy, grayish-white, highly malleable and ductile metallic element, resistant to most chemicals, practically unoxidizable except in the presence of bases, and fusible only at extremely high temperatures: used for making chemical and scientific apparatus, as a catalyst in the oxidation of ammonia to nitric acid, and in jewelry. Symbol: Pt; atomic weight: 195.09; atomic number: 78; specific gravity: 21.5 at 20°C.
a light, metallic gray with very slight bluish tinge when compared with silver.
made of platinum.
(of an audio recording) having sold a minimum of one million copies.
Origin of platinum
1Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024
British Dictionary definitions for platinum
/ (ˈplætɪnəm) /
a ductile malleable silvery-white metallic element, very resistant to heat and chemicals. It occurs free and in association with other platinum metals, esp in osmiridium: used in jewellery, laboratory apparatus, electrical contacts, dentistry, electroplating, and as a catalyst. Symbol: Pt; atomic no: 78; atomic wt: 195.08; valency: 1–4; relative density: 21.45; melting pt: 1769°C; boiling pt: 3827±100°C
a medium to light grey colour
(as adjective): a platinum carpet
Origin of platinum
1Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for platinum
[ plăt′n-əm ]
A soft, ductile, malleable, silver-white metallic element that usually occurs with osmium, iridium, palladium, or nickel. It has a high melting point and does not corrode in air. Platinum is used as a catalyst and in making jewelry, electrical contacts, and dental crowns. Atomic number 78; atomic weight 195.08; melting point 1,772°C; boiling point 3,827°C; specific gravity 21.45; valence 2, 3, 4. See Periodic Table.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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