Adjectives generally occur before Nouns in the sentence frame. They can be divided into two major classes, gradable and non-gradable.
NON-GRADABLE Adjectives denote absolute qualities such as nationalities or biological characteristics: one is either male or female, alive or dead, Australian or not Australian etc. Because they have this "either/or" quality, such adjectives often come in pairs where each word is the opposite or ANTONYM of its partner. True/false and married/single are other examples.
Non-gradable Adjectives are relatively uncommon. The majority of Adjectives are GRADABLE adjectives which measure qualities on a scale of size, value etc, such as young/old, tall/short, early/late.
Young/old are the key points on their scale, but other points can be slotted in. One's choice of word may vary according to one's own position on the scale: if you are twenty, then everyone over thirty may seem "old"! One's judgement in real-world terms also varies according to the scale. Thus a "tall child" would be shorter than a "tall man", a "tall Japanese" shorter than a "tall Norwegian", because the range of possible heights varies in each case. The same is true of adjectives denoting values: a "good party" has quite different characteristics from a "good lecture" or a "good talking-to".
If two scales are in use at once, then apparently nonsensical sentences make perfectly good sense:
This does not hold true for non-gradable adjectives:
Gradable adjectives can be modified by DEGREE ADVERBS (see 2.6):
They can be made into:
COMPARATIVES:
SUPERLATIVES:
Note that the more/most forms are preferred for adjectives of more than two syllables or unusual words.
Non-gradable adjectives don't fit these slots. However, like so many grammatical rules, these ones can be broken for stylistic or humorous effect. Sentence (16) should be unacceptable, but in the right context expresses the speaker's meaning very effectively:
16. That fish is very dead!