Notional grammars define adjectives as “words that describe nouns.” Big, cute, green, small, and wonky are prototypical adjectives. In big bully, The baby is cute, and I painted the wall green, each adjective describes a noun. Big describes the noun bully, cute describes the noun baby, and green describes the noun wall. However, stating that all words that describe nouns are adjectives is unequivocally wrong.
Nouns Versus Adjectives
The line between grammatical forms is blurry at best, especially among lexical categories. As closed classes that do not readily accept new member, functional categories such as pronoun, preposition, determiner, and conjunction are much clearer. But nouns are verbed, adjectives are nouned, and verbs are nouned and adjectived. (Notice the conversion of the nouns verb, noun, and adjective into verbs.) However, not all words that describe nouns are adjectives.
Grammatical form and grammatical function distinguish one word class from other. The internal structures, or grammatical form, that distinguish adjectives from other word classes are degrees of modification. Prototypical adjectives express three degrees of modification: positive, comparative, or superlative. The positive form is the base form of the adjective. The comparative form expresses a comparison between two entities in quality, quantity, or degree. The superlative form expresses the highest degree of comparison.
English has two parallel systems of comparison. The morphological system uses the suffixes –er and –est, with some anomalous forms. The syntactic system uses the adverbs more and most. For example:
- big – bigger – biggest
- cute – cuter – cutest
- green – greener – greenest
- small – smaller – smallest
- wonky – wonkier – wonkiest
- good – better – best
- bad – worse – worst
- adorable – more adorable – most adorable
- somnolent – more somnolent – most somnolent
All adjectives in English have a positive form. Not all adjectives have comparative and superlative forms. For example, prescriptive rules disallow comparisons of adjectives such as awake and pregnant. One is either awake or not. However, English speakers do use comparative and superlative forms of such adjectives as in I am more awake now and She is more pregnant than the last time I saw her.
The internal structures that distinguish nouns from other grammatical forms are number and possession. Prototypical nouns express number. Grammatical number refers to quantity. English nouns are singular or plural. Singular means one. Plural means not one. The majority of English nouns are regular, taking an -s suffix to form the plural. Irregular nouns follow other rules for forming the plural such as vowel and ending changes. Many irregular nouns are of foreign origin such as Latin and Greek. For example:
- baby – babies
- book – books
- box – boxes
- cat – cats
- dog – dogs
- owl – owls
- phone – phones
- train – trains
- child – children
- foot – feet
- mouse – mice
- person – people
- analysis – analyses
- cherub – cherubim
- fungus – fungi
However, although prototypical nouns express number, some categories such as noncount, uncountable, or mass nouns, cannot. For example, knowledge and furniture have only singular forms.
Prototypical nouns also express possession or lack therefore. Possessive nouns indicate a possession of or some other relationship to another word or phrase. In English, the affixation of the possessive clitic (‘s [apostrophe s] or s’ [s apostrophe]) forms possessive nouns. For example:
- baby – baby’s
- owl – owl’s
- today – today’s
- yesterday – yesterday’s
- Yuki – Yuki’s
- mother-in-law – mother-in-law’s
- James – James’
- princess – princess’
- children – children’s
- women – women’s
- babies – babies’
- monsters – monsters’
- owls – owls’
- ladies-in-waiting – ladies-in-waiting’s
Adjectives and nouns also perform different grammatical functions. The syntactic functions that distinguish adjectives from other grammatical forms are adjective phrase head, noun phrase modifier, subject complement, and object complement. An adjective phrase head is the nucleus of an adjective phrase. An adjective phrase consists of an adjective plus any modifiers and complements. A noun phrase modifier is a word, phrase, or clause that modifies or describes a noun including a pronoun or a noun phrase. A subject complement is a word, phrase, or clause that follows a copular, or linking, verb and describes the subject of the clause. The term predicate adjective is also used for adjective phrases that function as subject complements. An object complement is a word, phrase, or clause that directly follows and modifies the direct object. For example:
- disgustingly sweaty (adjective phrase head)
- afraid to fail (adjective phrase head)
- dark beer (noun phrase modifier)
- the bluest water (noun phrase modifier)
- Roses are red. (subject complement)
- He found the book questionable. (object complement)
The syntactic functions that distinguish nouns from other grammatical forms are noun phrase head, subject, subject complement, direct object, object complement, indirect object, prepositional complement, noun phrase modifier, determinative, appositive, and adjunct adverbial. A noun phrase head is the nucleus of a noun phrase. A noun phrase consists of a noun plus any determiners, modifiers, and complements. A subject is a word, phrase, or clause that performs the action of or acts upon the verb. The terms predicate nominative and predicate noun are also used for noun phrases that function as subject complements. A direct object is a word, phrase, or clause that follows a transitive verb and answers the question “who?” or “what?” receives the action of the verb. An indirect object is a word, phrase, or clause that indicates to or for whom or what the action of a ditransitive verb is performed. A prepositional complement is a word, phrase, or clause that directly follows a preposition and completes the meaning of the prepositional phrase. A determinative provides information such as familiarity, location, quantity, and number. Possessive nouns function as determinatives. An appositive is a word, phrase, or clause that modifies or explains another noun phrase. An adjunct adverbial is a word, phrase, or clause that modifies an entire clause by providing additional information about time, place, manner, condition, purpose, reason, result, and concession. For example:
- ninety-nine red balloons (noun phrase head)
- somebody to love (noun phrase head)
- Dogs make excellent pets. (subject)
- My grandparents were farmers. (subject complement)
- Lions eat impala. (direct object)
- America elected Barack Obama president. (object complement)
- Salespeople sell consumers goods. (indirect object)
- with apples (prepositional complement)
- because of ticks (prepositional complement)
- birthday cake (noun phrase modifier)
- child prodigy (noun phrase modifiers)
- baby’s toys (determinative)
- My aunts, teachers, assigned homework. (appositive)
Notice that adjectives and nouns can perform some of the same functions (subject complement, object complement, noun phrase modifier). Nouns cannot function as adjective phrase heads, and adjectives cannot perform many nominal functions. For example:
- Airplanes fly in the sky. (noun, subject)
- *Shiny fly in the sky. (adjective, subject)
- The woman bought jewelry. (noun, direct object)
- *The woman bought pretty. (adjective, direct object)
- Santa gives children presents. (noun, indirect object)
- *Santa gives nicest presents. (adjective, indirect object)
One seeming exception to the rule is the copular construction. Copular constructions refer to subject-copular verb-subject complement (S-CV-SC) constructions. Copular verbs are verbs such as be and seem that link the subject complement in the predicate to the grammatical subject. Both adjectives and nouns can function as subject complements as in The flowers are pretty and The flowers are roses. Inverse copular constructions switch the canonical word order from S-CV-SC to SC-CV-S. The inverted Pretty are the flowers and Roses are the flowers are possible in English, if not Yoda-esque. However, the word order changes in an inverse copular construction, not the functions of the noun or adjective.
Noun Phrase Modifiers
Adjectives are words that modify or describe nouns and other nominal forms. But not all words that describe nouns are adjectives. For example, both tasty and carrot modify the noun cake in the following examples:
- tasty cake
- carrot cake
Both words describe a noun, but only tasty is an adjective. Carrot is a noun.
As previously explained, grammatical form and grammatical function distinguish word forms. Both tasty and carrot function as noun phrase modifiers in tasty cake and carrot cake. However, tasty like other adjectives can express degrees of modification: tastier and tastiest. The noun carrot cannot express degrees of modification: *carroter cake and *carrotest cake. Carrot does, however, have plural and possessive forms: two carrots and carrot’s flavor. As an adjective, tasty does not have plural or possessive forms: *tasties and *tasty’s.
- man in the yellow hat (prepositional phrase)
- crying toddler (verb phrase or participial adjective)
- unencumbered assets (verb phrase or participial adjective)
- teacher handing the students the syllabus (verb phrase)
- lettuce eaten by rabbits (verb phrase)
- cookies to bake (verb phrase)
- dictionary that she referenced (adjective clause)
- vampire to whom she pledged her devotion (adjective clause)
Prepositional phrases, verb phrases, and adjective clauses also describe nouns but are not adjectives.
Noun and Adjectives
What about words like colors? In the sentence I like the reds, the word red is a noun. Reds is plural, which is an internal structure that distinguishes nouns from other grammatical forms. In I like the reddest one, the word red is an adjective. Reddest is a superlative form, which is an internal structure that distinguishes adjectives from other grammatical forms. Another example is the word human. In the sentence, To err is human, the word human is an adjective because the word can be compared as in To err is most human. Conversely, in the sentence The doctor needs human tissue, the word human is a noun because human can be moved into a prepositional phrase as in The doctors needs tissue of a human. Therefore, some words can be nouns or adjectives depending on the context.
Adjectives are words that describe nouns, but all words that describe nouns are not adjectives. Most notably, nouns often modify other nouns. Both big and kitchen describe table in big table and kitchen table. But only big can express degrees of modification — bigger and biggest — meaning big is an adjective. Kitchen has plural and possessive forms — kitchens and kitchen’s — making the word a noun. Even though both words perform the same grammatical function (noun phrase modifier), their internal structures differ, distinguishing the two different grammatical forms. Additionally, prepositional phrases, verb phrases, and adjective clauses can also modify nouns — because not all words that describe nouns are adjectives.
Brinton, Laurel J. & Donna M. Brinton. 2010. The linguistic structure of Modern English, 2nd edn. Amsterdam: John Benjamins Publishing Company.
Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.