Why is "dark" an adverb in "dark blue"?

Question

The sky is dark blue.

Source:

BBC English

Catherine: The sky is dark blue. The sky is dark blue.

Finn: So, is blue an adjective or adverb?

Catherine: It’s an adjective. Blue is describing the noun sky. Now number two: it's actually the same sentence but this time, think about the word dark. Is dark an adjective or an adverb?

Finn: The sky is dark blue.

Catherine: Right. So, is dark an adjective or adverb?

Finn: Dark here is an adverb.

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Thanks for the discussion.

It is interesting to read how the discussion is geared towards the possible explanations of the usage of dark as an adverb.

I've checked several dictionaries before starting this post. Dark is NOT an adverb. If dark is not an adverb, how and why can it be used as an adverb?

In this case, what is wrong to have dark as an adjective in the sentence?

Answer 1

The answer to the question “Why is dark an adverb in this sentence?” is that it is not one; that source is wrong. That’s because dark cannot ever be an adverb, let alone here. It’s just that color-words can behave somewhat curiously.

We have various related questions about this curiosity, including this one. John Lawler’s suspicion about color words having a special dispensation seems instructive:

John Lawler: Blue is the name of a color; names are usually nouns. I suspect we have a special dispensation for color words, like we do for many other semantically-crucial word sets.

Greg Lee: @JohnLawler, of course "blue" is a noun. I would never deny that, nor does McCawley. That's why, he reasons, it can be modified by the adjective "dark".

So it seems colors can be nouns for modification purposes in that they take adjectives to qualify them. The resulting multiword compound, the adjectivally qualified color like dark red or robin’s egg blue, is used to further describe another noun. The whole compound can then be qualified by intensifiers like very.

_{I'm guessing that we can use adjective ordering rules and perhaps constituency tests to show that the whole multiword part about the color counts as one single syntactic constituent. Therefore you must look at grammatical roles these phrases play in the grammar, not at the internal parts of speech of individual words within that phrase. Otherwise you get nonsense results the way you get when a gerund clause’s head VERB-ing word gets mistakenly called a noun when it’s really a verb. Calling it a noun is a common error — but calling is only a verb there at the start of this sentence, not a noun. I suspect this is the same class of error in calling dark an adverb when it’s actually an adjective.}

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What the Dictionary says...

Regarding blue, the OED says:

Often with modifying word indicating intensity (as bright blue, dark blue, light blue, etc.), drawing a comparison with an object or another colour (as indigo blue, lavender blue, powder blue, etc.), or making a (sometimes arbitrary) association with a person or thing (as French blue, royal blue, navy blue), etc.

But those “qualifying words” certainly are not adverbs. Indeed, the OED says that dark is an adjective when it has this color-related sense:

3c. Prefixed, as a qualification, to adjectives of colour: Deep in shade, absorbing more light than it reflects; the opposite of light. (Usually hyphened with the adj. when the latter is used attributively.)

And here are two citations provided of this:

• 1859 J. Ruskin Two Paths v. 202
  That lovely dark purple colour of our Welsh and Highland hills is owing, not to their distance merely, but to their rocks.
• 1863 M. L. Whately Ragged Life Egypt xvii. 163
  Clad in the ordinary dark-blue drapery.

Rubber Baby Buggy Bumpers

Why do they say this is an adjective? If you think it through, you’ll see why dark cannot be an adverb here, only an adjective.

What’s your favorite color?
Hot pink.
You mean like your hot pink sunglasses?
Exactly! All my sunglasses are hot pink!

If someone tells you their favorite color is hot pink, it seems reasonable to call pink a noun and hot an adjective. But now applying that to sunglasses doesn't swap around all the parts of speech into something new.

This happens with colors all the time:

• cerulean blue skies
• cherry red sunsets
• cobalt blue skies
• safety green vests
• royal purple stoles
• saffron yellow robes
• robin's egg blue eyes
• electric pink sunglasses

The last word in each of those noun phrases is a noun, but the first word of each is not an adverb. It is either a noun or an adjective in each case. Cobalt is a noun; it does not suddenly become an adjective when talking about a cobalt blue nor does it become an adverb when it is used in our cobalt blue skies

This is just like how tinted is not an adverb in tinted glass windows, or like how in the whole tongue-teaser rubber baby buggy bumpers, there are no adverbs nor even any adjectives.

Answer 2

Adjectives are used to describe nouns, i.e. the car is red.

Adverbs are most commonly used to describe verbs, i.e he fought valiantly

But adverbs can also describe adjectives. How is the car red? Is it blazingly red? Is it cheesily red? Cheekily red maybe?

That is the case for your sentence. The sky is blue. How is it blue? Darkly. It is not being blue lightly, it is being blue darkly.

BUT

It doesn't always need to be this way. One can also have adjective combinations, which would be what most would assume the sentence in question is employing. An adjective combination is where two conceptually separate adjectives join to describe one concept. Dark blue is an adjective, built by two, working in a combination. The sentence in question is ambigious in that sense, as we can't know whether it's an adverb describing an adjective, or an adjective combination. The only person that can really decide that, is the author. But in this case, it doesn't really matter which one it is, as the meaning remains the same either way.

Answer 3

It might be an adverb, or it might not be, depending on which "authority" you want to listen to. The English language has been around for much longer than our attempts to systematize it and slap labels on things, and our fumbling attempts to do so are crude at best. There's clearly no dispute here about meaning or usage, and it diagrams nicely either way, so I see no particular reason to be pedantic about it.

Answer 4

It's used as part of a set phrase which acts as an adjective. That being said, it's easy to imagine an adverb answering the question "how", as in

Q: "How blue is the sky?"
A: "It's dark blue." <- possibly an adverb, with the meaning that it's mostly black and a little bit blue

or

A: "It's slightly blue" <- definitely an adverb

Answer 5

I always think the words are not stuck to one part of the speech. They take positions depending on the usage. For eg. Parents are invited to an orientation (Parents - noun) There is a Parents' orientation Program on Sunday (here, I would say Orientation is a noun and Parents' is playing the role of an adjective)

Similarly, It is red. (red - adjective) It is dark red (anything that modifies an adjective is (also) an adverb by definition, so in this case, I would say 'dark' is an adverb)

Answer 6

About 60 years ago I was taught that when a word modifies the meaning of an adjective that modifying word is, by definition, an adverb. This was a hard and fast rule in the 60s.

Since then the rules and definitions for English grammar have gotten much more complicated.

Answer 7

"Dark" is Never an Adverb

Adjectives are very flexible, thanks to compound modifiers, but "dark" is never an adverb. First let's look at how flexibly it can be used in compound cases, but I'll explain why "dark" cannot ever be considered an adverb at the bottom.

What Adjectives Can Do

"dark-blue sky" forms a compound adjective ("dark-blue") modifying the noun, "sky", for example.

"dark blue sky" also tends to be interpreted the same way, although it's syntactically ambiguous without the hyphen since "blue" can also function as a noun. We can interpret it as a single adjective, "dark", modifying the compound noun, "blue sky" (similar to "dark beef soup"; "beef soup" is a compound noun and "dark" modifies it), or as a compound adjective "dark-blue", modifying "sky". This is just from a pure syntactical analysis; just about every reader will interpret this as a "dark-blue sky".

It's not just color adjectives that can form compounds. Consider a case like "light wooden door" or "soft feathery pillow" or "big creamy chicken noodle soup".

What Adjectives Can't Do

So compounds offer a great deal of flexibility, but the reason "dark" is never an adverb is that it can't do things like modify verbs. "The figure crept [dark] in the shadows," is grammatically incorrect. We need a real adverb such as "darkly" to modify "crept": "The figure crept [darkly] in the shadows."

When confused, focus more on what such words can't do rather than what they can and you'll then understand why a word like "dark" can only function as a noun or adjective, and never an adverb.

For example, "beef soup" might tempt someone to think "beef" could be used as an adjective, but consider the problem with using it in a context where an adjective is demanded: "He was very [beef]." It doesn't work even at the basic syntactical level. We need an actual adjective like "beefy". The dictionary will tell us when in doubt, but these quick litmus tests also reveal why "beef" is never an adjective, and "dark" is never an adverb.

Citations

Definition of "dark": https://www.merriam-webster.com/dictionary/dark

Note how it lacks an adverb definition.

Compound modifiers: https://en.wikipedia.org/wiki/Compound_modifier

Take note that hyphens can be omitted for compound adjectives, especially in unambiguous cases.

Accordingly, the phrase heavy metallic detector unequivocally employs a compound adjective to describe a weighty detector made of metal.

I've encountered some people thinking that only hyphenated pairs of adjectives form compound adjectives. That's not the case.

Answer 8

I am sure Dark in the sentence is an adjective in the form of a compound adjective that an adjective can be put before the other adjective.