intelligence quotientn. Abbr. IQ1. A number seen as a measure of a person’s intelligence, usually representing the person’s score on an intelligence test as expressed in relation to the scores of others who have taken the same test, with the average score set at 100.2. The ratio of tested mental age to chronological age, usually expressed as a quotient multiplied by 100. No longer in scientific use.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.intelligence quotient n (Psychology) a measure of the intelligence of an individual derived from results obtained from specially designed tests. The quotient is traditionally derived by dividing an individual’s mental age by his chronological age and multiplying the result by 100. Abbreviation: IQ Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014intel?ligence quo`tient n. an intelligence test score that is obtained by dividing mental age, which reflects the age-graded level of performance as derived from population norms, by chronological age and multiplying by 100: a score of 100 thus indicates a performance at exactly the normal level for that age group. Abbr.: IQ [1920?25] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.