molecular weight n the mass of a molecule that may be calculated as the sum of the atomic weights of its constituent atoms
* * *
the weight of a molecule of a substance as compared with that of an atom of carbon 12; it is equal to the sum of the atomic weights of its constituent atoms and is dimensionless (cf. molecular mass and molar mass). Abbreviated Mol wt or MW. Although widely used, the term is not technically correct; relative molecular mass (Mr>) is preferable.Medical dictionary. 2011.