Some adjectives can only be used to modify nouns, for example the adjective indoor. We can talk about:
But we don't usually say:
- *The pool was indoor (not good)
We call adjectives that appear before nouns attributive adjectives. The adjective indoor is called an attributive only adjective.
Other adjectives can't usually be used before a noun. We usually find these adjectives as the complements of verbs like BE, FEEL or BECOME. So we can say
- She was afraid
- She felt afraid
But we cannot say:
- *an afraid girl (not good)
Adjectives that we use like this are called predicative adjectives. The adjective afraid is a predicative only adjective.
We can use most adjectives as attributive adjective and predicative adjectives:
- a huge elephant
- The elephant was huge.
Sometimes we have two adjectives that look similar and mean the same thing. One of them is attributive only, and the other predicative only. For example, the adjectives live and alive. When these words are used to describe things that aren't dead, we use live as an attributive adjective and alive as a predicative adjective:
- a live snake
- The snake was alive.
- *an alive snake (wrong)
- *The snake was live. (wrong)
The term two-year old is used as an attributive only adjective phrase:
- a two year old whisky
- *The whisky was two year old (wrong).
The term two years old is used as a predicative only adjective phrase:
- *a two years old whisky (wrong)
- The whisky was two years old.
Similarly the following measure phrases only have attributive uses, where the noun part of the phrase has no plural inflection:
- twenty pound
- ten mile
- five minute
as in the following examples:
- a twenty pound note
- a ten mile journey
- a five minute meeting
In contrast, the following measure phrases where the noun part is plurally inflected can only be used predicatively:
- the meal was twenty pounds
- the journey was ten miles
- the meeting was five minutes
We can also use the term two year old as a nominal phrase. We can use it like a noun.:
- I have two children: a two year old and a three year old.
Notice that we use the attributive adjective here because we mean: a two year old child.
Hope this is helpful!