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 Cf. achievement quotient.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.