Traditionally, adjectives were considered one of the main parts of speech of the English language, although historically they were classed together with nouns. Nowadays, certain words that usually had been classified as adjectives, including the, this, my, etc., typically are classed separately, as determiners.
Adjective comes from Latin n?men adject?vum, a calque of Ancient Greek: , romanized: epítheton ónoma, lit. 'additional noun'. 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 type of noun. The words that are today typically called nouns were then called substantive nouns (n?men substant?vum). The terms noun substantive and noun adjective were formerly used in English but are now obsolete.
Depending on the language, an adjective can precede a corresponding noun on a prepositive basis or it can follow a corresponding noun on a postpositive basis. Structural, contextual, and style considerations can impinge on the pre-or post-position of an adjective in a given instance of its occurrence. In English, occurrences of adjectives generally can be classified into one of three categories:
Adjectives feature as a part of speech (word class) in most languages. In some languages, the words that serve the semantic function of adjectives are categorized together with some other class, such as nouns or verbs. In the phrase "a Ford car", "Ford" is unquestionably a noun but its function is adjectival: to modify "car". In some languages adjectives can function as nouns: for example, the Spanish phrase "uno rojo" means "a red [one]".
As for "confusion" with verbs, 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 in English is called a "big house". Such an analysis is possible for the grammar of Standard Chinese, for example.
Different languages do not use adjectives in exactly the same situations. For example, where English uses "to be hungry" (hungry being an adjective), Dutch, French, and Spanish use "honger hebben", "avoir faim", and "tener hambre" respectively (literally "to have hunger", the words for "hunger" being nouns). Similarly, where Hebrew uses the adjective ? (zaq?q, roughly "in need of"), English uses the verb "to need".
In languages that have adjectives as a word class, it is 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).
Many languages (including English) distinguish between adjectives, which qualify nouns and pronouns, and adverbs, which mainly modify verbs, adjectives, or other adverbs. Not all languages make this exact distinction; many (including English) have words that can function as either. For example, in English, fast is an adjective in "a fast car" (where it qualifies the noun car) but an adverb in "he drove fast" (where it modifies the verb drove).
A German word like klug ("clever(ly)") takes endings when used as an attributive adjective but not when used adverbially. (It also takes no endings when used as a predicative adjective: er ist klug, "he is clever".) Whether these are distinct parts of speech or distinct usages of the same part of speech is a question of analysis. It can be noted that, while German linguistic terminology distinguishes adverbiale from adjektivische Formen, German refers to both as Eigenschaftswörter ("property words").
Linguists today distinguish determiners from adjectives, considering them to be two separate parts of speech (or lexical categories). But formerly determiners were considered to be adjectives in some of their uses.[a] Determiners are words that are neither nouns nor pronouns, yet reference a thing already in context. They generally do this by indicating definiteness (a vs. the), quantity (one vs. some vs. many), or another such property.
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 adverbs modifying 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").
In many languages (including English) it is possible for nouns to modify other nouns. Unlike adjectives, nouns acting as modifiers (called attributive nouns or noun adjuncts) usually are not predicative; a beautiful park is beautiful, but a car park is not "car". The modifier often indicates origin ("Virginia reel"), purpose ("work clothes"), semantic patient ("man eater") or semantic subject ("child actor"); however, it may generally indicate almost any semantic relationship. It is also common for adjectives to be derived from nouns, as in boyish, birdlike, behavioral (behavioural), famous, manly, angelic, and so on.
In Australian Aboriginal languages, the distinction between adjectives and nouns is typically thought weak, and many of the languages only use nouns--or nouns with a limited set of adjective-deriving affixes--to modify other nouns. In languages that have a subtle adjective-noun distinction, one way to tell them apart is that a modifying adjective can come to stand in for an entire elided noun phrase, while a modifying noun cannot. For example, in Bardi, the adjective moorrooloo 'little' in the phrase moorrooloo baawa 'little child' can stand on its own to mean 'the little one,' while the attributive noun aamba 'man' in the phrase aamba baawa 'male child' cannot stand for the whole phrase to mean 'the male one.' In other languages, like Warlpiri, nouns and adjectives are lumped together beneath the nominal umbrella because of their shared syntactic distribution as arguments of predicates. The only thing distinguishing them is that some nominals seem to semantically denote entities (typically nouns in English) and some nominals seem to denote attributes (typically adjectives in English).
Many languages have special verbal forms called participles that can act as noun modifiers (alone or as the head of a phrase). Sometimes participles develop into pure adjectives. Examples in English include relieved (the past participle of the verb relieve, used as an adjective in sentences such as "I am so relieved to see you"), spoken (as in "the spoken word"), and going (the present participle of the verb go, used as an adjective in such phrases as "the going rate").
Other constructs that often modify nouns include prepositional phrases (as in "a rebel without a cause"), relative clauses (as in "the man who wasn't there"), and infinitive phrases (as in "a cake to die for"). Some nouns can also take complements such as content clauses (as in "the idea that I would do that"), but these are not commonly considered modifiers. For more information about possible modifiers and dependents of nouns, see Components of noun phrases.
In many languages, attributive adjectives usually occur in a specific order. In general, the adjective order in English can be summarised as: opinion, size, age or shape, colour, origin, material, purpose.  Other language authorities, like the Cambridge Dictionary, state that shape precedes rather than follows age.
Determiners--articles, numerals and other limiters (e.g. three blind mice)--come before attributive adjectives in English. Although certain combinations of determiners can appear before a noun, they are far more circumscribed than adjectives in their use--typically, only a single determiner would appear before a noun or noun phrase (including any attributive adjectives).
This means that, in English, adjectives pertaining to size precede adjectives pertaining to age ("little old", not "old little"), which in turn generally precede adjectives pertaining to colour ("old white", not "white old"). So, one would say "One (quantity) nice (opinion) little (size) old (age) round (shape) [or round old] white (colour) brick (material) house." When several adjectives of the same type are used together, they are ordered from general to specific, like "lovely intelligent person" or "old medieval castle".
This order may be more rigid in some languages than others; in some, like Spanish, it may only be a default (unmarked) word order, with other orders being permissible. Other languages, such as Tagalog, follow their adjectival orders as rigidly as English.
The normal adjectival order of English may be overridden in certain circumstances, especially when one adjective is being fronted. For example, the usual order of adjectives in English would result in the phrase "the bad big wolf" (opinion before size), but instead, the usual phrase is "the big bad wolf".
Owing partially to borrowings from French, English has some adjectives that follow the noun as postmodifiers, called postpositive adjectives, as in time immemorial and attorney general. Adjectives may even change meaning depending on whether they precede or follow, as in proper: They live in a proper town (a real town, not a village) vs. They live in the town proper (in the town itself, not in the suburbs). All adjectives can follow nouns in certain constructions, such as tell me something new.
In many languages, some adjectives are comparable and the measure of comparison is called degree. 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 comparison. Some languages do not distinguish between comparative and superlative forms. Other languages allow adjectives to be compared but do not have a special comparative form of the adjective. In such cases, as in some Australian Aboriginal languages, case-marking, such as the ablative case may be used to indicate one entity has more of an adjectival quality than (i.e. from--hence ABL) another. Take the following example in Bardi:
Jalnggoon boordij=amba niwarda-go
Jalnggoon big-SUBR niwarda-ABL
Jalnggoon oysters are bigger than niwarda oysters
In English, many adjectives can be inflected to comparative and superlative forms by taking the suffixes "-er" and "-est" (sometimes requiring additional letters before the suffix; see forms for far below), respectively:
Some adjectives are irregular in this sense:
Some adjectives can have both regular and irregular variations:
Another way to convey comparison is by incorporating the words "more" and "most". There is no simple rule to decide which means is correct for any given adjective, however. The general tendency is for simpler adjectives and those from Anglo-Saxon to take the suffixes, while longer adjectives and those from French, Latin, or Greek do not--but sometimes sound of the word is the deciding factor.
Many adjectives do not naturally lend themselves to comparison. For example, some English speakers would argue that it does not make sense to say that one thing is "more ultimate" than another, or that something is "most ultimate", since the word "ultimate" is already absolute in its semantics. Such adjectives are called non-comparable or absolute. Nevertheless, native speakers will frequently play with the raised forms of adjectives of this sort. Although "pregnant" is logically non-comparable (either one is pregnant or not), one may hear a sentence like "She looks more and more pregnant each day". Likewise "extinct" and "equal" appear to be non-comparable, but one might say that a language about which nothing is known is "more extinct" than a well-documented language with surviving literature but no speakers, while George Orwell wrote, "All animals are equal, but some animals are more equal than others". These cases may be viewed as evidence that the base forms of these adjectives are not as absolute in their semantics as is usually thought.
Comparative and superlative forms are also occasionally used for other purposes than comparison. In English comparatives can be used to suggest that a statement is only tentative or tendential: one might say "John is more the shy-and-retiring type," where the comparative "more" is not really comparing him with other people or with other impressions of him, but rather, could be substituting for "on the whole" or "more so than not". In Italian, superlatives are frequently used to put strong emphasis on an adjective: bellissimo means "most beautiful", but is in fact more commonly heard in the sense "extremely beautiful".
Attributive adjectives and other noun modifiers may be used either restrictively (helping to identify the noun's referent, hence "restricting" its reference) or non-restrictively (helping to describe a noun). For example:
In some languages, such as Spanish, restrictiveness is consistently marked; for example, in Spanish la tarea difícil means "the difficult task" in the sense of "the task that is difficult" (restrictive), whereas la difícil tarea means "the difficult task" in the sense of "the task, which is difficult" (non-restrictive). In English, restrictiveness is not marked on adjectives but is marked on relative clauses (the difference between "the man who recognized me was there" and "the man, who recognized me, was there" being one of restrictiveness).
In some languages, adjectives alter their form to reflect the gender, case and number of the noun that they describe. This is called agreement or concord. Usually it takes the form of inflections at the end of the word, as in Latin:
|puella bona||(good girl, feminine singular nominative)|
|puellam bonam||(good girl, feminine singular accusative/object case)|
|puer bonus||(good boy, masculine singular nominative)|
|pueri boni||(good boys, masculine plural nominative)|
|buachaill maith||(good boy, masculine)|
|girseach mhaith||(good girl, feminine)|
Often, distinction is made here between attributive and predicative usage. In English, adjectives never agree, whereas in French, they always agree. In German, they agree only when they are used attributively, and in Hungarian, they agree only when they are used predicatively:
|The good (Ø) boys.||The boys are good (Ø).|
|Les bons garçons.||Les garçons sont bons.|
|Die braven Jungen.||Die Jungen sind brav (Ø).|
|A jó (Ø) fiúk.||A fiúk jók.|