Some adjectives are used as nouns to describe groups of people. Each of these groups follows the determiner the (definite article). There are the blind, the deaf, the elderly, the homeless, the old, the rich, the sick, the young, etc.

Examples:

  • The injured were in the thousands.
  • Every year, millions join the ranks of the unemployed worldwide.
  • There seems to have no plans to provide cheap housing for the homeless.