Solution that contains high percentage of the base in solution are called?

Basic solution.

Explanation:

Solution that contains high percentage of the base in solution are called basic solution because it has more amount of 'Hydroxl or Hydroxide' ions or (OH-) ions. When we put few drops of the red litmus solution or paper in the solution which contains high percentage of the base, it turns red colour in to blue.

So, here the blue colour indicates that the solution is basic in nature.

Alkalis are the Solutions that contains high percentage of the base in solution