Dictionary.com
definitions

body mass index

noun
  1. an index for assessing overweight and underweight, obtained by dividing body weight in kilograms by height in meters squared: a measure of 25 or more is considered overweight. Abbreviation: BMI
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for body mass index

body mass index

noun
  1. an index used to indicate whether a person is over- or underweight. It is obtained by dividing a person's weight in kilograms by the square of their height in metres. An index of 20–25 is normalAbbreviation: BMI
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
body mass index in Medicine

body mass index

n.
  1. A measurement of the relative percentages of fat and muscle mass in the human body, in which mass in kilograms is divided by height in meters squared and the result used as an index of obesity.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
body mass index in Science

body mass index

[bŏd′ē]
  1. A measurement of the relative percentages of fat and muscle mass in the human body, in which weight in kilograms is divided by height in meters squared. The result is used as an index of obesity.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.