3. An adjective is a "describing word", the
main syntactic role of which is
to qualify a noun or noun phrase, giving more
information about the object signified.[1]
Adjectives are one of the traditional
English parts of speech, although historically
they were classed together with the nouns.
Certain words that were traditionally
considered to be adjectives,
including the, this, my, etc., are today usually
classed separately, as determiners

4. Examples
•That's an interesting idea. (attributive)
•That idea is interesting. (predicative)
•Tell me something interesting.
(postpositive)
•The good, the bad, and the ugly.
(substantive)

5. Etymology…
Adjective comes from Latin (nōmen) adjectīvum "additional
(noun)",[2] a calque of Ancient Greek: ἐπίθετον
(ὄνομα) epítheton (ónoma) "additional (noun)".[3][4] In the
grammatical tradition of Latin and Greek, because adjectives
were inflected for gender, number, and case like nouns (a
process called declension), they were considered a subtype
of noun. The words that are today typically called nouns
were then called substantive nouns (nōmen
substantīvum).[5] The terms noun substantive and noun
adjective were formerly used in English, until the
word noun came to refer only to the former type, and the
second type came to be known simply as adjectives.

6. Types of use[edit]
A given occurrence of an adjective can generally be classified
into one of three kinds of use:
Attributive adjectives are part of the noun phrase headed by
the noun they modify; for example, happy is an attributive
adjective in "happy people". In some languages, attributive
adjectives precede their nouns; in others, they follow their
nouns; and in yet others, it depends on the adjective, or on
the exact relationship of the adjective to the noun. In English,
attributive adjectives usually precede their nouns in simple
phrases, but often follow their nouns when the adjective is
modified or qualified by a phrase acting as an adverb. For
example: "I saw three happy kids", and "I saw three kids happy
enough to jump up and down with glee." See also Postpositive
adjective.
Predicative adjectives are linked via a copula or other linking
mechanism to the noun or pronoun they modify; for
example, happy is a predicate adjective in "they are happy"
and in "that made me happy." (See also:Predicative
expression, Subject complement.)
Nominal adjectives act almost as nouns. One way this can
happen is if a noun is elided and an attributive adjective is left
behind. In the sentence, "I read two books to them; he
preferred the sad book, but she preferred the happy", happy is
a nominal adjective, short for "happy one" or "happy book".
Another way this can happen is in phrases like "out with the
old, in with the new", where "the old" means, "that which is
old" or "all that is old", and similarly with "the new". In such
cases, the adjective functions either as a mass noun (as in the
preceding example) or as a plural count noun, as in "The meek
shall inherit the Earth", where "the meek" means "those who
are meek" or "all who are meek".

7. Distribution[edit]
Adjectives feature as a part of speech (word class) in most,
but not all, languages. In some languages, the words that
serve the semantic function of adjectives may be
categorized together with some other class, such
as nounsor verbs. For example, rather than an adjective
meaning "big", a language might have a verb that means "to
be big", and could then use an attributive verb construction
analogous to "big-being house" to express what English
expresses as "big house". Such an analysis is possible for
the Chinese languages, for example.
Different languages do not always use adjectives in exactly
the same situations. For example, where English uses to be
hungry (hungry being an
adjective), Dutch and French use honger hebben and avoir
faim respectively (literally "to have hunger", the words for
"hunger" being nouns). Similarly, where Hebrew uses the
adjective ‫זקוק‬zaqūq (roughly "in need of"), English uses the
verb "to need".
In languages which have adjectives as a word class, they are
usually an open class; that is, it is relatively common for new
adjectives to be formed via such processes as derivation.
However, Bantu languages are well known for having only a
small closed class of adjectives, and new adjectives are not
easily derived. Similarly, native Japanese adjectives (i-
adjectives) are considered a closed class (as are native
verbs), although nouns (an open class) may be used in
the genitive to convey some adjectival meanings, and there
is also the separate open class of adjectival nouns (na-
adjectives).

8. Adjective phrases[edit]
Main article: Adjective phrase
An adjective acts as the head of an adjective
phrase or adjectival phrase (AP). In the
simplest case, an adjective phrase consists
solely of the adjective; more complex adjective
phrases may contain one or
more adverbsmodifying the adjective
("very strong"), or one or
more complements (such as "worth several
dollars", "full of toys", or "eager to please"). In
English, attributive adjective phrases that
include complements typically follow the noun
that they qualify ("an evildoer devoid of
redeeming qualities").

9. Comparison of adjectives[edit]
Main articles: Comparison (grammar) and Comparative
In many languages, some adjectives are comparable. For example, a person may be "polite",
but another person may be "more polite", and a third person may be the "most polite" of the
three. The word "more" here modifies the adjective "polite" to indicate a comparison is being
made, and "most" modifies the adjective to indicate an absolute comparison (a superlative).
Among languages that allow adjectives to be compared, different means are used to indicate
the comparison. Many languages do not distinguish comparative from superlative forms.
In English, there are three different means to indicate comparison: most simple adjectives take
the suffixes "-er" and "-est", as
"big", "bigger", "biggest";
a very few adjectives are irregular:
"good", "better", "best",
"bad", "worse", "worst",
"old", "elder", "eldest" (in certain contexts only; the adjective is usually regular)
"far", "farther/further", "farthest/furthest"
"many", "more", "most" (usually regarded as an adverb or determiner)