ˈbody mass ˌindex noun [uncountable] (
abbreviation BMI)
the relationship between your height and your weight, used as a measure of whether you have too much flesh on your body:
Your body mass index is your weight in kilograms divided by the square of your height in meters. Individuals with a BMI of 25 to 29.9 are considered overweight. [TahlilGaran] Dictionary of Contemporary English ▲