Definition for Intelligence quotient
From Biology Forums Dictionary
Intelligence quotient (IQ)
1) 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.
2) A score derived from standardized tests that is calculated by dividing the individual's mental age (determined by the test) by his or her chronologic age, and multiplying the quotient by 100.