IR

Dictionary.com Unabridged

Ir

Irish ( def 4 ).

Ir

Symbol, Chemistry.

ir-

1
variant of in-2. (by assimilation) before r: irradiate.

ir-

2
variant of in-3. (by assimilation) before r: irreducible.

Ir.

I.R.

1.
immediate reserve.
2.
infantry reserve.
3.
intelligence ratio.
4.
internal revenue.
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Collins
World English Dictionary
ir
 
the internet domain name for
Iran

Ir
 
the chemical symbol for
iridium

IR
 
abbreviation for
1.  infrared
2.  (in Britain) Inland Revenue
3.  Iran (international car registration)

Ir.
 
abbreviation for
1.  Ireland
2.  Irish

ir-
 
prefix
in- a variant of in-

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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American Heritage
Medical Dictionary

Ir
The symbol for the element iridium.

ir- 1
pref.
Variant of in-1.

ir- 2
pref.
Variant of in-2.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
Ir  
The symbol for iridium.
iridium   (ĭ-rĭd'ē-əm)  Pronunciation Key 
Symbol Ir
A rare, whitish-yellow element that is the most corrosion-resistant metal known. It is very dense, hard, and brittle, and is is used to make hard alloys of platinum for jewelry, pen points, and electrical contacts. 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 Periodic Table.

Our Living Language  : In 1978 geologist Walter Alvarez discovered a high concentration of iridium in a layer of clay that had formed between the Mesozoic and Cenozoic eras, a period about 65 million years ago during which dinosaurs and many other organisms became extinct. This finding was significant as iridium is rare at Earth's surface (an unusually high concentration is called an iridium anomaly). Most surface iridium is thought to come from dust created when meteors disintegrate in the atmosphere or collide with Earth. Alvarez's father, the physicist Luis Alvarez, suggested that the iridium might have come from the impact of a meteor about 10 km (6.2 mi) across. Such an impact would have caused an enormous explosion, sending huge clouds of dust into the atmosphere. The dust, blocking out the Sun and causing extensive acid rain, would have triggered a worldwide ecological disaster. Many scientists think that such a disaster caused the extinction of the dinosaurs and at least 70 percent of all other species alive at the time, including most of Earth's land plants. Geologists have since found iridium deposits in rocks of a similar age in more than 100 places worldwide. Scientists in the early 1990s identified a large impact crater in the Yucatán peninsula of central Mexico that is the same age as the iridium deposit found by Alvarez. It is 200 km (125 mi) wide and may have been caused by the same impact.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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FOLDOC
Computing Dictionary

IR definition


1. Internet Registry.
2. infrared.
(1997-01-30)

ir definition

networking
The country code for Iran.
(1999-01-27)

The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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American Heritage
Abbreviations & Acronyms
Ir
iridium
IR
  1. information retrieval

  2. infrared

  3. Iran (international vehicle ID)

Ir.
Irish
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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