Noun

1. The atomic weight of an element or radical divided by its valence; the molecular weight of a compound divided by its combining power in a specific reaction.
   • 1888, Thomas Sterry Hunt, A New Basis for Chemistry, page 149

     In the proportion d : p :: 1 : v, as applied to any liquid or solid species, p does not represent its real equivalent weight, but the weight of the normal species which, by its condensation, gives rise to the liquid or solid.

   • 1922, Leicester F. Hamilton, Calculations of Analytical Chemistry, page 38,

     The equivalent weight of an element or compound is that weight equivalent in reactive power to one atomic weight of hydrogen.