Usage of THE + ADJECTIVE
Some of the adjectives denote human qualities. When the article THE is placed before such an adjective it becomes a plural noun, and therefore takes a plural verb; e.g.
a) the deaf (= deaf people)
b) the disabled (= disabled people)
c) the healthy (= healthy people)
d) the living (= living people)
e) the poor (= poor people)
f) the sick (= sick people)
g) the unemployed (= unemployed people)
i) The rich are not always happy.
ii) The dishonest deserve punishment.
iii) The poor GET poorer; the rich GET richer.
NOTE-I: THE can be used in the same way with national adjectives ending in CH, SH, SE or SS; e.g.
the Dutch, the Spanish, the Welsh, the Burmese, the Chinese, the Japanese, the Swiss [It is possible for these to have a singular meaning.]
NOTE-II: THE + COULOR can be used in the plural to represent people but these take ‘S’ like nouns; e.g.
a) the blacks (= black people)
b) the whites (= white people)
NOTE-III: THE + ADJECTIVE can sometimes have a singular meaning such as, the accused, the unexpected; e.g.
The judge awarded death penalty to THE ACCUSED of the murder case.