English adjectives

What is substantivized adjectives in English?
for example: the poor, the old

[RonBee]

Substantive adjectives are adjectives that can be used as nouns. (You have provided a couple of good examples of that.)

• Substantive
  USE:
  A Substantive is a term covering all words that can function like a noun, including nouns, the gerund, the adjectival noun and the pronoun.
  http://www.usingenglish.com/glossary/substantive.html

Example:

• The bold seize the day, while the timid run away.

:)

[Tdol]

The term I use is adjectival noun:
http://www.usingenglish.com/glossary...ival-noun.html

We use them whenever we wish to talk in general about the people or whatever that are represented by that adjective.