Can a noun work as an adjective, and the adjective as a noun?

Question

Hazel Eyes

I found the following paragraph in the guycounseling.com blog article “Hazel Eyes: Learn Why People with Greenish Eye Color are Rare!”, containing the two words “hazel eyes”:

Hazel eyes are fascinating to gaze into. When you look at someone who has hazel eyes, you see colors that are completely different than other eye colors, such as crystal blue or emerald green.

—Guy Counseling Site

I also found some text on another site that says:

Her eyes are hazel.

Hazel is a noun that denotes a colour; how can hazel modify the noun eyes if hazel is also a noun itself? Doesn’t a word always have to be an adjective to modify a noun? Isn’t that what “adjective” means by its very definition: a word that modifies a noun? How can something modify a noun without being an adjective? Is that even possible?

The dictionary entry for hazel I found on the online Oxford Living Dictionaries website doesn’t mention that hazel can ever be adjective; it mentions only that it is a noun:

hazel

ɴᴏᴜɴ

1. A temperate shrub or small tree with broad leaves, bearing prominent male catkins in spring and round hard-shelled edible nuts in autumn.

   ^{Genus Corylus, family Betulaceae: several species, in particular the common Eurasian hazel (C. avellana)}

2. [mass noun] A reddish-brown or greenish-brown colour, especially of a person’s eyes.

   [as modifier] ‘the laughing hazel eyes were serious now’

—Oxford Living Dictionaries

How can this be grammatical?

Her eyes (noun) are hazel (noun)?

And also, if you accept that a noun can work as an adjective, then, can adjective work as a noun?

Answer 1

Two different facts are needed to thoroughly answer this question.

First, Hazel is both an adjective and a noun. Online dictionaries can be hit-and-miss in quality. Even high-quality dictionaries make mistakes, or will be abridged, and different lexicographers have to pick and choose what to leave out. When researching a topic like this, you owe it to yourself to check more than one dictionary. (Maybe even invest in a high-quality PRINT dictionary.) For example, Merriam-Webster online shows Hazel is both an adjective and a noun, but you have to scroll the page about a third of the way down to find the adjective form: https://www.merriam-webster.com/dictionary/hazel

And the American Heritage online dictionary also lists it as both a noun and an adjective: https://ahdictionary.com/word/search.html?q=hazel

Dictionary.com also shows it as both a noun as an adjective, but you need to scroll to see the adjective listing: http://www.dictionary.com/browse/hazel?s=t

By the way, Oxford Dictionaries seems inconsistent in their parts-of-speech classification of colors. Red and green are listed as both nouns and adjectives. If you look up amber, it's listed only as a noun, but one of the example sentences actually uses it as a modifier for eye color:

1.1 A honey-yellow colour typical of amber.

• 'her eyes were green flecked with amber'
• [as modifier] 'amber eyes'

Second, parts-of-speech in English aren't as clear-cut as they are sometimes taught. The part-of-speech of a word often depends on how it is used. It's very common for a noun to act as an adjective. (In fact, it happens so often, that I'm surprised this hazel eyes example might be the first time it's come to your attention.) Examples are a "pet store," a "shoe factory," a "couch cushion," or a "cucumber sandwich." Nouns that act like adjectives are called "attributive nouns," and this page gives an overview:

https://learningenglish.voanews.com/a/everyday-grammar-when-nouns-act-like-adjectives/2998821.html

Incidentally, verbs can also modify nouns, the so-called "attributive verbs": https://en.wikipedia.org/wiki/Attributive_verb

So either way, whether you accept hazel as an actual adjective, or a noun acting like an adjective, the expression "hazel eyes," is grammatical.

Can an adjective act as a noun? Colloquially, yes. If offered hot or cold tea, I might answer, "I'll have the hot." Or a customer in a hardware store may ask an attendant: "Where is your electrical?" (Meaning where is your electrical section.) I'd be wary of using similar constructions in formal speech or writing. You can see several other examples on this StackExchange page: Is there a term for the use of adjectives as nouns?

Answer 2

In a comment, BillJ wrote:

I'd take "hazel" to be an adjective, so in the NP "hazel eyes", "hazel" is an adjective modifying "eyes". And in "Her eyes are hazel", "hazel" is an adjective as predicative complement.

Answer 3

In a comment, NigelJ wrote:

'Hazel' is only a noun when it applies to 'a type of deciduous shrub or tree' or when it applies to the actual colour called 'hazel'. Otherwise it is an adjective describing something that is 'of the colour, hazel' OED.

Answer 4

Hazel in your example is a colour name, and hence functioning as an adjective. Some colour names are adjectives in their own right (e.g. red, brown, yellow, etc), and many others are derived from nouns denoting a coloured thing. An orange is a fruit; indigo is a plant from which a dye is made, a violet is a flower; hazel is a plant with greenish-brown parts. Some shades of green are described as 'avocado'; some greys are 'charcoal'.

Answer 5

Not in general. There are a few contexts where this is possible, but not nearly as many as in many other languages. In phrases like car seat, a common noun is modifying another noun to mean “the seat of a car”, and the David Beckham rule has a proper noun modify another noun to mean “the rule that was made for David Beckham.”

An example of an adjective being used as a noun would be, “Fortune favors the bold,” or “The meek shall inherit the earth.” You can’t do this without the definite article, or even in general: you couldn’t drop the word one from, “I want the red one,” nor “Give the bold one a cookie.” Thinking about it, it seems to apply only to generalizations about people with a characteristic.

I would call hazel in hazel eyes an adjective in context. It’s a modifier describing or qualifying the noun eyes. Hazel can also function as a noun in other contexts, such as, “Hazel is a lovely color.” There, it is the subject of the sentence. However, the Oxford Living Dictionary disagrees with me and gives “The laughing hazel eyes were serious now,” as the example sentence for what it defines as a noun. Merriam-Webster does likewise. Some other dictionaries, including the Oxford English Dictionary, have a second definition listed as an adjective. I suspect the ones that do not treat hazel eyes as shorthand for the more poetic eyes of hazel, parallel to how cat eyes are the eyes of a cat.

For what it’s worth, modern descriptive linguistics doesn’t think the categories of noun and adjective must be mutually exclusive in every language.

Answer 6

Hazel (Old English: hæsl, hæsel) is of Proto-Germanic: hasalaz. It is related to the Dutch hazelaar meaning ‘hazel tree’ and hazelnoot meaning ‘hazelnut’.

Interestingly, Shakespeare was the first to use it in print, in reference to the reddish-brown colour of eyes in his 1592 play: Romeo and Julliet. Presumably, inspired by the colour of ripe hazel nuts produced by the hazel tree. This is seen when Mercutio accuses Benvolio:

"Thou wilt quarrell with a man for cracking Nuts, hauing no reason, but because thou hast hasell eyes".

Presumably before Middle English, hazel was a noun denoting the tree and a "modifier" when referring to the physical aspects of the tree. In this sense it was an evaluative adjective (something that can be measured and compared):

hazel trees (quantitative)
hazel nuts (quantitative)

I'm guessing the colour "hazel" is a descriptive adjective which tell us more about the non-measurable properties of an object, such as the hazelnuts produced from a hazel tree. For example, when a person claims you are eyes are hazel, or hazelnuts are hazel in colour. These are all being used in the subjective sense unless there are qualifiers for what constitutes a colour to be hazel.

So for example in:

Your eyes are hazel
His eyes are hazel
Your hair has a hazelnut colour

Here hazel is a descriptive adjective.

Similarly, when referring to the measurable aspects of the hazel tree, it is being used evaluatively (it is referring to the tree*):

*A hazel tree has measurable, scientific characteristics of what makes a "hazel tree" "hazel". Hazel is the genus of a tree species.

I gathered 5 hazel nuts from the hazel tree
10 hazel nuts fell from 5 hazel trees.

For example you cannot quantify hazel when referring to the colour and to subjective qualities:

? Your eyes are hazel = are they or is it just the lighting?
? There's 100 hazel eyes in the room = 50 people = 50 people in the room have hazel eyes?
? There are 5 hazel coloured pencils in the room = The 5 coloured pencils are hazel?

Through context it is deducible whether hazel is being used evaluatively or descriptively.

Notice the difference between:

That tree is hazel (descriptive adjective)
That tree is a hazel tree. (evaluative adjective)

---

Whether "hazel" in

"That tree is a hazel tree"

or

"You have hazel eyes"

functions as a modifier or is an adjective, depends on the lexicon (dictionary) you consult.

Essentially, 1) "You have hazel eyes" and 2) "Your eyes are hazel" mean the same to ODO. While true, syntacticly they're not. In 1) hazel is a modifier and in 2) an adjective.

ODO would cite "hazel" as only as a modifier and not an adjective:

Whereas, Cambridge has 2 separate lexical categories for "hazel" (the colour):

I believe this is the same for "hazel" when referring to the tree. For example, you can't say:

? The tree was hazel

for it to definitely mean "The hazel tree"; it has to be affixed to -tree to remove ambiguity:

The tree was a hazel tree

Similar to hazel nut:

? The nut was hazel (to mean hazel nut?)
? The nut that was hazel was nice
(c.f. The hazel nut was nice)

Hazel in "hazel nut" could be a noun functioning as a modifier where only the noun hazel to refer to the type of tree, exists, since there is not a separate lexical category of an adjective to describe "parts of a hazel tree", unlike its colour counterpart.

Answer 7

Hazel is a nut tree. The hazelnut is pale brown and in the same way as orange is a fruit and a colour, both can be nouns or adjectives in the right context.

That said, using a noun as a modifier for another noun doesn't always make it an adjective. 'Pocket knife' for instance is a compound noun and so is 'race car'.