4. What is a solvent?

A solvent (from the Latin solvō, "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution ... Water is a solvent for polar molecules and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within a cell.

something in which you dissolve another substance/able to dissolve other substances.

Explanation:

Some examples of solvents are water, ethanol, toluene, chloroform, acetone, milk, etc.