Dictionary
molec'ular weight'
Chem.
the average weight of a molecule of an element or compound measured in units once based on the weight of one hydrogen atom taken as the standard or on
1/16 the weight of an oxygen atom, but after 1961 based on
1/12 the weight of the carbon-12 atom; the sum of the atomic weights of all the atoms in a molecule.
Abbr.: mol. wt. Also called
formula weight. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.