from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A very hard and brittle, exceptionally corrosion-resistant, whitish-yellow metallic element occurring in platinum ores and used principally to harden platinum and in high-temperature materials, electrical contacts, and wear-resistant bearings. Atomic number 77; atomic weight 192.2; melting point 2,410°C; boiling point 4,130°C; specific gravity 22.42 (at 17°C); valence 3, 4. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A metallic chemical element (symbol Ir) with an atomic number of 77.
from the GNU version of the Collaborative International Dictionary of English
- n. A rare metallic element of atomic number 77, of the same group as platinum, which it much resembles, being silver-white and indifferent to most corrosive agents, but harder, more brittle, and with a higher melting temperature (2410° C, versus platinum 1772° C). With the exception of osmium, it is the heaviest substance known, its specific gravity being 22.4. Symbol Ir. Atomic weight 192.22.
from The Century Dictionary and Cyclopedia
- n. Chemical symbol, Ir; atomic weight, 193. A metal of silver-white color, belonging to the platinum family, and, so far as known, always present in native platinum.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium
From Latin īris, īrid-, rainbow (from the colors produced by dissolving it in hydrochloric acid); see irido- + -ium.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek ἶρις ("rainbow") (because of the bright colour of many of iridium's salts). (Wiktionary)