molecular weight

noun

Chemistry.

1. 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 (0.0625) the weight of an oxygen atom, but after 1961 based on 1/12 (0.083) the weight of the carbon-12 atom; the sum of the atomic weights of all the atoms in a molecule. mol. wt.

molecular weight

noun

1. the former name for relative molecular mass

molecular weight

1. The sum of the atomic weights of the atoms contained in a molecule.

2. Also called relative molecular mass

molecular weight

1. The sum of the atomic weights of all the atoms in a molecule.

Word History and Origins

Origin of molecular weight¹

First recorded in 1875–80