aqueous solution

solution in which water is the solvent, water based solution

An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations as a subscript (aq). The word aqueous means pertaining to, related to, similar to, or dissolved in water. As water is an excellent solvent as well as naturally abundant, it logically has become a ubiquitous solvent in chemistry.
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Noun
1. a solution in water
(hypernym) solution

 Say it 
(aq) A substance dissolved in water.

SOLUZIONE ACQUOSA