body mass indexˈbody 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.
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.