What is an adjective?
An adjective is a word that defines, qualifies or modifies the meaning of a noun, or more rarely of a pronoun. It expresses the qualities or attributes of the word it qualifies. There are two main categories of adjectives: a) determining adjectives, and b) descriptive adjectives .

■ Types of Adjective
1. Determining adjectives :
Also called limiting adjectives, these are words that are more often referred to as determiners, and are dealt with elsewhere. There is a limited number of these words. They are notably possessive adjectives (such as my, their), numerals and quantifiers (such as one, two, three, every, many), demonstrative adjectives (such as this or that), interrogative adjectives (such as which). To learn about the use of these determining adjectives, please consult the appropriate pages.
2. Descriptive adjectives
Descriptive adjectives (such as big, English, wonderful) describe the permanant or perceived qualities of a noun; their number is unlimited. New descriptive adjectives enter the language every day, often in the fertile world of slang. There are two categories of descriptive adjectives;
2.1. qualificative or qualifying adjectives , such as big, nice, complicated which express the passing or perceived qualities of a noun, and
2.2. classifying adjectives (including absolute adjectives) such as married, second, hydraulic, unique, dead which express permanent qualities or absolutes. Qualifiying adjectives are "gradable", i.e. it is possible to graduate their intensity, by the addition of an adverb of degree, such as very, quite, enough; most qualifying adjectives can also be put into comparative or superlative forms (big, bigger, biggest). Classifying adjectives cannot be graded: a person is either married, or not, or dead, or not; he or she cannot be "very married", nor "more dead" than another person, at least not under normal usage of the words. That being said, many adjectives can be used either as qualifying adjectives, or as classifying adjectives, depending on the context. Take the example of the adjective old. Examples: My car is very old (qualifying, with a noun) He is intelligent (qualifying, with a pronoun) see Pronouns) The old computer was much quieter than the new model (classifying)
In the first example above, old is a perceived quality, and therefore gradable, in the second old has an absolute value, with the meaning of former or previous.
See gradation and comparison of adjectives below.

■ Use of adjectives
Adjectives are used in two main ways; they can either be attributive or they can be predicative.
Attributive adjectives :
This is the most common use of adjectives, standing next to a noun in a noun phrase. In English, simple and complex adjectives almost always come before the noun . Examples: The big metal box My dear old grandfather . A very modern plastic dish. An easily recognisable face. A pink and green dress A not-too-infrequent event.

Exceptions:
There are only a very small number of exceptions, notably concerned involved, present and responsible, which have a particular meaning when they come after a noun. There are also some cases in which old and tall follow the noun The other important case when an adjective will follow a noun is when the adjective is postmodified by a prepositional phrase. Examples: All the people concerned were told to leave the room. The man is two metres tall. I'm 20 years old. The children present did not like the show. (=The children who were present ....) I bought all the bottles left in the shop. He was a man proud of his success For details on the ordering of adjectives within a noun group, see adjective order.
Predicative adjectives
Adjectives are said to be predicative when they are used as the complement of the verb to be, or other similar verbs such as get, become, grow, etc. Examples: The result was magnificent. My girlfriend is beautiful . The weather is getting colder. I grew fonder of London after living there for a month.
In English, adjectives never take a plural inflexion (s), not even on the rare occasions when they are used as nouns, such as in The poor. We cannot say the poors.

■ Formation of adjectives in English
Many adjectives are lexical words in their own right, i.e. they exist independently of any other word, or are the root word of a word family. For example good, bad, ugly.
Other adjectives are inflected forms of other words, derived notably from verbs. For example charming, lost. Other adjectives can be formed from nouns, for example beautiful (from beauty) or motionless (from motion), or even from other adjectives (for example yellowish). One of the beauties of the English language is the simplicity with which words can be formed from other words: all that is needed is to add the appropriate ending, and a new word is made. Here are some examples. Examples: Unthinkable, doable, mendable, possible, plausible - with -able or -ible Careless, fruitless, homeless, motionless - with less Beautiful, hopeful, wonderful, awful, blissful - with ful Soggy, foggy, lazy, stormy, skinny, bloody, - with -y Smallish, greenish, darkish, - with -ish Distinguished, bored, displaced, contented, squared - with -ed Challenging, alarming, amazing, exciting - with -ing
Comparison of adjectives
Many qualifying adjectives can be used in a comparative or a superlative form. In most cases, the comparative form of an adjective is made with the word more, and the superlative form with the word most. But with most common short monosyllabic adjectives, and some two-syllable adjectives, the comparative is made by adding the ending -er, and the superlative with the ending -est There are two common adjectives with irregular comparative and superlative forms: good, better, best, and bad, worse, worst. Examples: Careful, more careful, most careful Difficult, more difficult, most difficult, Certain, more certain, most certain Hard, harder, hardest, Black, blacker, blackest, Old, older, oldest, Clever, cleverer, cleverest, Large, larger, largest (just add -r and -st to adjectives ending in e) Big, bigger, biggest , hot, hotter, hottest (final p t k b d g n & m are doubled unless proceeded by a long vowel, or diphthong, as in harder or quieter) Pretty, prettier, prettiest , heavy, heavier, heaviest (adjectives ending in y have inflected forms in -ier and -iest)
Gradation of adjectives
Qualifying adjectives can be graded by adverbs of intensity or of degree, and by some other adverbs. The most common adverbs of intensity are: quite, rather, fairly, very, extremely, highly
These adverbs come before the adjective. But note the following points:
Enough: qualifying an adjective, enough comes, exceptionally, after the word it qualifies (examples 6 and 7). (Qualifying a noun, enough comes before the word it qualifies).
Rather and quite : used attributively, quite and rather can either follow the article, or come before the article: i.e. we can choose between a rather good book and rather a good book, or quite a nice guy and a quite nice guy. With rather, the choice is generally open, with quite it is more usual to say quite a than a quite. Adjectives that are in the comparative form can be modified by intensifiers such as much, far and sometimes by adverbs of degree (examples 8). Some kinds of adjectives, notably participles, can be modified by a wide range of adverbs (examples 9 and 10). Examples: I'm quite certain I left my hat in the car. This is a rather good restaurant OR this is rather a good restaurant. It's very clear that you have read the book already. This is a highly complicated situation to be in. This situation is highly complicated. OK, that was a clear enough reply. Is the door wide enough to get through ? That was much better than last time. It's rather better than I expected. They are a newly married couple. He made a carefully worded statement.