aquavalent

aquavalent Chem.

(əˈkwævələnt)

[f. L. aqua water + valēnt-em pr. pple. of valēre to be strong, to equal; cf. equivalent.]

The molecular proportion between an anhydrous salt and the water of its cryohydrate, i.e. the number of molecules of water with which one molecule of the salt unites.

in Watts Dict. Chem. VIII. 1005.