A solution is dilute if it
has a little amount of solute dissolved
On the basis of the concentration of solute, a solution can be classified as a dilute and concentrated solution. A solution is said to be dilute if it has relatively a little amount of solute dissolved in the given amount of solvent. A dilute solution is always an unsaturated solution. In other words, dilute solutions have less concentration. Whereas, a concentrated solution contains a relatively large amount of solute dissolved in the given amount of solvent.
For example, at a given temperature, let's suppose a maximum of 25 g of sugar can be dissolved in 100 mL of water. So, if 2 g of sugar is added in 100 mL of water it will form a dilute solution