noun, plural isos. Television Slang.

by shortening; cf. -o Unabridged


incentive stock option.
International Standardization organization.
the numerical exposure index of a photographic film under the system adopted by the International Standardization Organization, used to indicate the light sensitivity of the film's emulsion.


a combining form meaning “equal,” used in the formation of compound words: isochromatic; in chemistry, used in the names of substances which are isomeric with the substance denoted by the base word: isocyanic acid.
Also, especially before a vowel, is-.

< Greek, combining form of ísos equal Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
ISO (aɪsaʊ)
International Organization for Standardization
[Greek isos equal; often wrongly thought to be an abbreviation for International Standards Organization]

iso- or (before a vowel) is-
combining form
1.  equal or identical: isomagnetic
2.  indicating that a chemical compound is an isomer of a specified compound: isobutane; isocyanic acid
[from Greek isos equal]
is- or (before a vowel) is-
combining form
[from Greek isos equal]

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

iso- or is-

  1. Equal; uniform: isobar.

  2. Isomeric: isopropyl.

  3. Characterized by sameness with respect to species: isoantigen.

  4. Characterized by sameness with respect to genotype: isograft.

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
ISO   (ī'ěs-ō')  Pronunciation Key 
An organization, the International Organization for Standardization, that sets standards in many businesses and technologies, including computing and communications. The term ISO is not an abbreviation, but instead derives from the Greek word īsos, meaning equal.
  1. A prefix that means "equal," as in isometric, "having equal measurements."

  2. A prefix used to indicate an isomer of an organic compound, especially a branched isomer of a compound that normally consists of a straight chain. The isomer is characterized by a Y-shaped branch at the end of the chain that consists of two "prongs". Each prong consists of one carbon atom. Thus isopentane contains five carbon atoms like normal pentane, but arranged as a chain of three carbons plus a Y-shaped branch of two carbons at the end.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Computing Dictionary

ISO definition

International Organization for Standardization

The Free On-line Dictionary of Computing, © Denis Howe 2010
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American Heritage
Abbreviations & Acronyms
  1. in search of

  2. International Organization for Standardization (technically not an initialism—term is based on the prefix iso —, from the Greek isos, meaning “equal”)

  3. intraseasonal atmospheric oscillation

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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