What is the term for a liquid composed of polar molecules?

A dissolving liquid composed of polar molecules is a polar solvent.

The distinction of polar and non-polar liquids is important because the like dissolves like rule. This rule states that the solubility is greater when the polarity of the liquid is similar to the polarity of the solute.

So, to dissolve polar compounds (e. g. ionic compounds) you should use polar solvents (e. g. water).

Answer: polar solvent