Use

We use adjectives as nouns to describe groups of people who have something in common.

Example:

This is a  game for both the young and the old.

Explanation:

Young and old are both adjectives, but they are used as nouns in this sentence that talk about the group of people who are young and the group of people who are old.

How to build

By putting the definite article (‘the’) before an adjective, you can turn it into a noun.

More Examples

• The bold and the reckless love extreme sports.

• Only the rich can afford business class tickets.

• Many organizations collect donations of food for the homeless.