Considering that:
- The antonym of day is night.
- The antonym of light can be either darkness or obscurity.
Is there any exact antonym for daylight, a word that would mean "the darkness of the night", the same way daylight means "the light of day"?
I would use darkness in a conversation, but darkness is not necessarily associated with the night : it could be used to describe a dark room even when it's sunny outside. However, daylight cannot be used to describe a room lightened by a light bulb when it's dark outside.
Edit : I do not specifically look for a word recognised by a dictionary. A neologism used by a published author, and a culture reference would also be interesting.
Edit 2 : From tchrist's answer, it is now clear that no single-word expression exists for the concept I'm talking about (which is why I accepted the answer). However, moonshine, moonlight cannot match correctly since they define light, when the question is about defining night darkness. This reminds me of something Einstein once supposedly said to a teacher :
There is no such thing as darkness. Darkness is nothing but the absence of light.
From this, while it is possible to stand in the daylight, one couldn't stand in night darkness, since darkness is nothing to be standing in. Similarly, while you can be in water, you can't actually be in dryness.
Best Answer
TL;DR — You aren’t likely to find something perfectly suitable through your approach to creating a compound word with both parts flipped. Folks normally use either in the dark or else by dark or by night to oppose in/by daylight. However, you might try moonshine.
Dictionary Sources
The OED gives several examples of nightblack used to mean as dark as night, including these two:
It also attests the existence of night-dark, as in this citation:
What’s an Antonym?
I don’t think you will ever get a one-word opposite of daylight that fits perfectly in all places where daylight is used. Daylight a very old word dating from the thirteenth century which has come to be used in numerous ways:
The top twenty collocations from COCA that immediately precede daylight are in order of occurrence broad, during, before, eastern, into, see, until, full, bright, still, local, saw, natural, pacific, enough, fading, central, seen, open, and ambient.
The top twenty collocations from COCA that immediately follow daylight are in order of occurrence hours, time, saving, savings, left, between, basement, came, film, outside, raids, streams, faded, comes, fades, bombing, attack, raid, revealed, and pours.
Your antonym presumably has to work in most of those places, and I don’t think you are going to come up with one. You appear to believe that one can derive a reversible antonym of a compound word by inverting each of its pieces and putting them back together again. That is not going to work in the general case, and it does not in general work here in this specific one either. These are almost none of them sensible:
As you see, most of those just don’t work at all. Sometimes you even find yourself back to the same place you started due to “double negation”, such as when you oppose sunup with shadedown — which would mean the same thing.
Published Examples
I’m not very fond of question that ask for neologisms, since that becomes nothing but a list question. However, because you limited it to actual published words, there is some small hope of rescuing your question.
Now, you have chosen to limit the sense of daylight to the first one I listed above, which also happens to be its oldest use: the light of day, the day’s light. That’s unfortunate because the only reasonable opposite for light of day is dark of night.
However, you do often find moonshine used as an opponent to daylight. For example:
On the other hand, you have by night opposing by daylight here:
Neither of those are new words; they’re just what people use, and so probably what you should use as well.
If you had elected the “sunrise” sense instead, there actually are neologisms coined by published authors for what the opposite of that would be. For example, Gene Wolfe uses shadelow and shadeup in his Book of the Short Sun and Book of the Long Sun portions of his Solar Cycle.
It’s too bad you have chosen the “light of day” sense of daylight, because Wolfe’s coinings are appealing for describing the dark and shady period between shadelow and shadeup.