[ ahy-soh ]

noun,plural i·sos.Television Slang.

Origin of iso

By shortening; cf. -o

Other definitions for ISO (2 of 3)


  1. incentive stock option.

  2. Trademark. International Organization for Standardization.

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

Other definitions for iso- (3 of 3)


  1. 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.

Origin of iso-

From Greek, combining form of ísos “equal”
  • Also especially before a vowel, is-. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use iso in a sentence

British Dictionary definitions for ISO (1 of 2)


/ (aɪsaʊ) /

  1. International Organization for Standardization

Origin of ISO

Greek isos equal; often wrongly thought to be an abbreviation for International Standards Organization

British Dictionary definitions for iso- (2 of 2)


combining form
  1. equal or identical: isomagnetic

  2. indicating that a chemical compound is an isomer of a specified compound: isobutane; isocyanic acid

Origin of iso-

from Greek isos equal

Collins 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 ISO (1 of 2)


[ ī′ĕs-ō ]

  1. 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.

Scientific definitions for iso- (2 of 2)


  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.

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