Today I had an English class with my hardworking students who asked very smart questions during a ten-minute break. They asked me about definite article ‘the’. Certain adjectives can be used with the definite article to talk about groups of people; For example, The unemployed are losing their last hope!
She’s collecting money for the blind.
Those expressions have a plural meaning: the dead means ‘the dead people’ or ‘all dead people’, but not ‘the dead man!’. There are not very many expressions of this kind in English. The most common are. Let’s look at the list below
the mentally ill
Most other adjectives cannot be used in this way. For instance, you cannot normally say THE FOREIGN, THE HAPPY or THE DISGUSTING in order to refer to groups of people.
Some information about definite article but I think it’s enough for you.