Dictionary.com
definitions

formula weight

noun Chemistry.
  1. (of a molecule) molecular weight.
  2. (of an ionic compound that does not form molecules) the sum of the atomic weights of the atoms of the formula unit.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
formula weight in Medicine

formula weight

n.
  1. molecular weight
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.