body mass index: a measure of someone's weight in relation to height; to calculate one's BMI, multiply one's weight in pounds and divide that by the square of one's height in inches; overweight is a BMI greater than 25; obese is a BMI greater than 30
index: a number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time
fly-fishing: angling with an artificial fly as a lure